Not seen, observed, or paid attention to by anyone.
Prefix 'un-' (not) plus 'noticed' from Latin 'notare' (to mark or note). The prefix was added in English to create the opposite meaning.
The prefix 'un-' is one of English's most powerful tools—it can negate almost any adjective, but 'unnoticed' is poignant because it describes the human fear of being overlooked or forgotten by everyone.
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