嫌(きら)い, which means 'to dislike', is a frequently used な-Adjective found in a wide variety of Japanese phrases. Like verbs, all な-Adjectives alter their form based on what follows them in a sentence.

In the case of 嫌(きら)い, it uses な when it directly modifies a noun, and だ (or the formal です) when it functions as the predicate of a sentence. This change depends on whether the adjective is describing a noun that comes after it, or if it is completing the main idea of the sentence on its own.

• ホラー映画(えいが)は嫌(きら)いだ。
  I don't like horror movies. (Horror movies are unpleasant)
• 私(わたし)は虫(むし)が嫌(きら)いです。
  I dislike bugs. (To me, bugs are unpleasant)
• 妹(いもうと)の嫌(きら)いな野菜(やさい)はピーマンです。
  The vegetable my little sister dislikes is green peppers. (The vegetable that is disliked, by her)

When used with だ, 嫌(きら)い makes a direct statement that something is 'unpleasant'. In contrast, when used with な, it describes the quality of 'being disliked' and applies it to the noun that it modifies.

Just as 大(だい) can be added to 好(す)き to intensify it to 'love', it can also be added to 嫌(きら)い to create the much stronger meaning of 'hate'.

• 大(だい)嫌(きら)いな歯医者(はいしゃ)に行(い)く。
  I'm going to the dentist that I hate.

Caution

Even though it ends with い, remember that 嫌(きら)い is a notable exception that functions as a な-Adjective, so it's a good idea to commit this to memory.