In Japanese it is called 連体修飾語 (for a word) or 連体修飾節 (for a phrase). 連体修飾 means modification or description of a noun, or in Japanese 体言に連なる修飾.
As suggested by the word “prenominal”, it is placed before a noun. Eg:
手の込んだ 料理
Here, 手の込んだ is placed before and describes 料理.
Usually, 連体形 of 用言 (動詞, 形容詞 and 形容動詞) is used as 連体修飾語. 手の込んだ is also a 連体形.
手 (名詞) の (助詞) 込ん (連用形 of 動詞 “込む”) だ (連体形 of 助動詞 “た”)