English
timer
From time (verb) + -er.
Proto-Indo-European *deh₂y- ‘to divide’
…
Proto-Germanic *tīmô ‘division, period; time’
Proto-West Germanic *tīmō
Old English tīma ‘time, period’
Middle English tyme
English time
Today it means
noun A device used to measure amounts of time.
Language periods are conventional ranges, not dates for this word.
Etymograph / timer