Timely means happening at just the right moment. A timely warning, a timely reminder, timely intervention.
It is praise for the timing rather than the thing, and a timely reminder is often a polite way of saying somebody had forgotten. It is an adjective despite the -ly ending, which catches people out: things happen in a timely manner rather than timely.
1adjectivetimelyHappening at just the right moment.
“Thanks to the timely arrival of the ambulance, the man survived.”
timely is a quality.
Old English timlic, time plus -ly. The -ly here makes an adjective rather than an adverb.
Old English
*tīmlīc
Middle English
timely
English, today
timely
Built from
From Middle English timely, tymely, timliche, from Old English tīmlīc and tīmlīċe (“in good time; timely; soon”), equivalent to time + -ly. Cognate with Danish timelig, Swedish timlig, Icelandic tímalegur, tímanlegur.
Etymology from Wiktionary, CC BY-SA