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.