Meaning of the brackets at kanji reading
 

When I read meanings of kanji the hiragana sometimes show brackets. For example niku(i) niku(mu) niku(gara). But what do they mean?

As I hope you already know, Japanese cannot be written in kanji only. Many words consist of both kanji and kana.

In your particular dictionary, it seems that they put the kana parts of the words in the brackets.

憎い = niku(i)

憎む = niku(mu)

The hiragana/romaji found in the kanji inside the brackets, these can be used to create different meanings... Like:

話し　hana(shi) - to talk

話そう　hana(sou) - lets talk

The romaji/hiragana in the brackets just change the meaning depending on what you use grammatically.