"Although she seems to lack emotion, this is largely a pretense."
— The Talosians, Star Trek: The Original Series
Kuudere: A stock love interest who is calm and collected on the outside, and never panics. They show little emotion, and in extreme cases are completely emotionless, but may be hiding their true emotions. They tend to be leaders who are always in charge of a situation.
A kuudere, sometimes written as kūdere or just kudere, refers to a character who is often cold, blunt, and cynical. They may seem very emotionless on the outside, but on the inside they’re very caring — at least when it comes to the ones they love.
The last well-known one, the kuudere girls, are those girls that look expressionless, won't react to whatever the guy says, doesn't get jokes, is usually of white or blue hair and most likely regarded as some sort of genius of high IQ or whatever.
The point of kuudere is that, though they're introduced as something like moving ice statues, as they develop their relationship for the guy they start opening up and even actually showing expressions like smiling lightly and stuff.
In some cases, a kuudere will completely melt or break their ice armor, start crying or screaming "I love you," etc. This is when a kuudere goes from kuu mode to dere mode. It's one of the possible developments when you have a kuudere archetype.
Allegorically speaking, a kuudere is like snow: it may be cold and harsh at first glance but it is also what keeps autumn's seeds warm and safe until spring.
Similarly, while perhaps appearing apathetic and awfully pragmatic, it is but a frosty mask that protects tender, delicate feelings deep underneath the facade, waiting for someone to melt the snow and allow them to blossom.
Kuuderes often speak in a calm monotone and seem unaffected by the world around them. They never seem to be overly happy, excited, or surprised - just as they never appear sad, annoyed, or angry. Extreme examples may even seem to be completely emotionless. It is used to describe characters who always remain calm and composed. Though they act serious on the outside, they often have a very good, sarcastic sense of humour. They tend to have deep love for someone (they have a good personality when you know them) but are afraid to show it too often because they view it as a weakness, either because of who they are or because of the situation they are in. More often than not, they come off as emotionless, acting very cold, blunt and cynical.
Sometimes, kuuderes are the class presidents that keep their schools running. Other times they take the form of stoic, professional assistants to superiors that they love and respect.
While kuuderes remains strict and business-like, they are emotional underneath their self-control. However, they tend to fear showing any weakness such as admitting liking someone or coming to rely on someone emotionally as well as professionally. Some, are unclear as to how to even express said emotions—and in extreme cases, are unsure what feelings actually mean.
Due to the way a Kuudere acts, a Yangire can easily pretend to be a Kuudere when not acting insane.
The difference between a Kuudere and a Dandere is that Dandere characters don't talk because of shyness, while Kuuderes choose willingly to not talk, only doing so without fear when necessary. Danderes are nervous and embarrassed with others, contrary to Kuuderes, who don't show emotions and can control their feelings.
The difference between a Kuudere and a Hinedere is that Kuuderes don't care about some things, making them look expressionless in a lot of situations, while Hinederes show a similar expression due to annoyance. Hinederes will snap easily to people if they begin to irritate them, while Kuuderes will remain their cool.
Meaning of the Word
Kuudere Word Meaning
The kuu in kuudere クー comes from the word kuuru クール, which is the katakanization of the English word "cool."
In Japanese, kuuru can mean a lot of things. It can means someone looks chill, calm or even cold, or exterminator-like badass whenever something happens, or even impressive, like it does in English. In the case of kuuderes, the kuuru would be the the composed, calm type. The type that doesn't show emotions and stays cool no matter what.
Sometimes you may see kūdere instead of kuudere. This is just the same word written with different romaji, Neither are wrong.
Type 1 — Always In Control: Comes off as "kuu-" (cool) because of emotional control, maintaining a calm, collected exterior. Expressions are subtle, with watery eyes being akin to bawling, and a small smile being akin to a giggle fit. Feelings may be filtered through snark or dry wit. The appeal is their bluntness and directness, in contrast to shy reserve or boisterous rowdiness. If playing a Love Interest, either the other partner will be the source of "Will They or Won't They?", or they'll skip that and the focus will be on the drama that comes after they admit "They Do". Occasionally this is a trait of a more exaggerated character, the "Emotionless Girl".
Type 2 — Once You Get To Know Them: They will show the 'dere' side, but strangers and the untrusted will see the 'kuu' side. Friends all consider them to be caring and in private moments with them you may just catch them laughing. Although it will still be considered unusual. It's not that they spare friends any of the "Deadpan Snarker" wit or that they don't act 'kuu' with them sometimes. The friends just understand it better than those that aren't close.
Type 3 — Mood-Swinger: Alternating between 'kuu-' and 'dere' persona depending on mood. What controls the mood? Some may have clearly defined "Berserk Buttons". Companions might learn how to manipulate this to their advantage. Others might switch moods at what seems to be random moments, which can be very unnerving or confusing to those nearby. Some might contend that this version isn't 'kuu-' (cool) enough to qualify as a kuudere, and might place them in some other category.
Obviously these variations aren't always used pure, and often are mixed together in different characters. Using Raven from Teen Titans as an example, while she fits the first variation best, she certainly has elements of the other two.
A coodere refers to a character who is very similar to a Kuudere, but instead turns lovestruck.
Cooderes may not seem like they care about anything, but they actually do. They start cold, distant, uninterested, and don't pay any attention to potential love interests, but eventually turn lovestruck. Unlike a kuudere, cooderes don't get hostile with other characters, and instead, they ignore them. Cooderes develop feelings, while kuuderes have them all along but keeps them hidden.
Meaning of the Word
The “coo” in coodere comes from a more English like version the Japanese pronunciation of the English word “cold” (courudo, コールド), and "deredere" (デレデレ), which means "lovey dovey".
A combination of Kuudere and Tsundere.
Kuutsundere  are a type of dere that are basically a cross between a Kuudere and Tsundere. There are 2 main types of Kuutsunderes, the Temperic type and the Apathetic type.
The Temperic type of Kuutsundere, which like the name suggests is temperic by nature, can sometimes stay calm/cool, head/level head (or at least appear dat way) individuals, other times they are hothead individuals. They may also take a while to warm up to their crush or a potential love interest.
The Apathetic type are more apathetic, abstracted, and often show little (to not) emotions or not very emotional. They also seem very sarcastic and rude at times, or other times can be very sarcastic and rude.
During the development of the plot, they may not reveal the Dere-sides at all, since they are most often second-plan characters. Kuutsundere, unlike Tsundere, do not hide their feelings behind a mask of sarcasm, but express their true feelings, in addition, they do not have such sharp mood swings as Tsundere.
The word is a compound of "tsun tsun" (ツンツン), meaning to turn away in disgust and ''kuudere'' which is a combination of cool (クール) and "deredere" (デレデレ), which means "lovey dovey".
A kuugire  is a subtype of the kuudere. They are characters which, under further development, reveal a more brutal and violent side instead of the typical loving and caring side. However, such characters in some cases may show a dere-side, but it is not the leading one in their case.
Kuugires may have sadistic personality traits and a passion for destruction, or treat people with contempt and without any sympathy, but they act aloof, cold, calculating, not showing their emotions and their attitude to what is happening around them. From yandere as such, kuugire differ in the absence of mental disorders and sudden mood swings (which is a sign of "bipolar disorder"). Kuugire are almost always antagonists and/or negative characters.
Please note: Characters who kill against their will and feel compassion for their victims are not kuugires.
Meaning of the word
The “kuu” in kuudere comes from the Japanese pronunciation of the English word “cool” (クール), and thus, is used for a person who is calm and composed on the outside, and "gire" (ギレ) that means "to be mad (at someone)".
What is Gire ギレ?
The suffix gire ギレ is sometimes added to these personality words instead of dere デレ. Its meaning in words such as tsungire and yangire is that of "snapping" or "being mad" instead of dere's "being in love."
The word gire comes from the verb kireru キレる, which means "to snap" or "to be mad (at someone or something)." Basically to be full of it. To lose your patience. To be done with. To have had the last drop. To burst with anger. To get the last string holding your anger down cut. That's what kireru means.
The gire versions of personalities often have nothing to do with love or romance at all. People often attribute ~gire as more violent versions of ~dere, but these two words aren't actually related. A character deemed ~gire doesn't even need to be in a romance or anything. They just lean towards aggressive, abusive or violent behavior.
The part of the word kireru that becomes the suffix is kire, but it becomes gire instead because of a process called rendaku that changes the pronunciation of suffixes.