Deculture (デカルチャー de-karucha-) is a Zentradi / Meltrandi expression of shock and surprise. It was first used in The Super Dimension Fortress Macross: Do You Remember Love?, then later in Macross 7, Macross Frontier, as well as Macross Δ, and its theatrical adaptation, Macross Δ Movie: Passionate Walküre.
In context, "Deculture" can be translated to human language as "shocking", "incomprehensible" "unbelievable" or "unexpected".
The prefix "Yack" is sometimes added. Though it's generally translated to 'this" or "something", the resulting words Yack Deculture (ヤック・デカルチャー yakku de-karucha-) also take on a negative meaning that denotes "something unbelievably horrible", "this unthinkable thing" or "something crazy".
The Zentradi however, do not stick to this rule consistently. There are times that when faced with a situation that would warrant the prefix, they just blurt out "Deculture" standalone instead. The opposite also happens sometimes, leading to exaggeration. 
After Space War I, humans and Zentradi started to coexist with one another on Earth. When the Immigration fleets were mobilized years later, this relationship extended to various parts of the galaxy.
As a result, the word "Deculture" was also adopted into human language. The current usage however is a far cry from before. It now describes something "amazing" or "great". The prefix Yack was also dropped from everyday use but a few people (mostly of Zentradi lineage) are aware of it and use the term loosely on occasion. 
Among the ranks of the Zentradi, the original context has remained more or less intact when using their own language barring exceptions.
Notes And TriviaEdit
- Many Limited Items/Special Footage in the series are often referred to as "Deculture" Editions, using the adopted human language context.
- Deculture is part of the catchphrase of Nyan-Nyan's commercial jingle in Macross Frontier, as well as being the term used in the final eyecatch after the preview. Instead of saying "See you next episode", the line goes "See you next Deculture".
- The term is used in the Walküre song, Koi! Halation THE WAR.
- In Macross Δ Scramble, Ernest Johnson sometimes says "Yack Deculture" when he is selected as a support character.
- Also in Delta Scramble, Klan Klang sometimes exclaims "Deculture" (human context) when the player is doing well on a mission, both as a wingmate or support character.