word with difficult-to-read kanji
A linguistic term for words whose kanji are hard to read, often due to irregular readings, rare characters, or lack of phonetic clues.
"海月" is one example of a word with difficult-to-read kanji; it is read "kurage".
For learners of Japanese, words with difficult-to-read kanji can be a major hurdle.
Compound of 難読 (nandoku, 'difficult to read') + 語 (go, 'word'). The term is a modern linguistic coinage.