Noun which may take the genitive case particle 'no', Noun
not under observation; not on one's radar; unnoticed
よりによって相手がノーマークのスーちゃんなんて。That it be with the off-the-radar Sue of all people! unmarked (player); unguarded; uncovered
Sports
unmarked (item, etc.); without a mark
Also written ノー・マーク