a brief record of points or ideas written down as an aid to memory

I'll make a note in my diary

lecture notes

a short informal letter or written message

I left her a note explaining where I was going

a banknote

a ten-pound note

a single tone of definite pitch made by a musical instrument or the human voice

the last notes of the symphony died away

a particular quality or tone that reflects or expresses a mood or attitude

there was a note of scorn in her voice

the decade could have ended on an optimistic note

notice or pay particular attention to (something)

he noted his mother's unusual gaiety

please note that you will not receive a reminder that final payment is due

record (something) in writing

he noted down her address on a piece of paper