usage: discover or determine the existence, presence, or fact of; "She detected high levels of lead in her drinking water"; "We found traces of lead in the paint"
2. notice, mark, note
usage: notice or perceive; "She noted that someone was following her"; "mark my words"
3. comment, notice, remark, point out, note, observe, mention, remark
usage: make or write a comment on; "he commented the paper of his colleague"
4. notice, acknowledge, react, respond
usage: express recognition of the presence or existence of, or acquaintance with; "He never acknowledges his colleagues when they run into him in the hallway"; "She acknowledged his complement with a smile"; "it is important to acknowledge the work of others in one's own writing"
1. noticed (vs. unnoticed), detected
usage: being perceived or observed; "an easily noticed effect on the rate of growth"