non-response; no answer
Used in surveys, questionnaires, or formal contexts when someone does not reply or leaves a question unanswered.
アンケートで無回答の項目が多かった。
There were many unanswered items in the questionnaire.
無回答の場合は集計から除外します。
Non-responses will be excluded from the tally.
Compound of 無 (mu, 'without') and 回答 (kaitō, 'answer, reply').