If we have a "second" of time, what's "first"? [closed]

The English word minute in the time sense (and the various similar European words) came from Latin 'pars minuta prima' or 'first small part'; when it became necessary to subdivide even further, the obvious term was 'pars minuta secunda' which became second and its various cognates. (Best explained in Etymonline.)

I.e. primary and secondary division by 60, where one minute is 1/60th part. Minute here refers to part and originates from "minutus" meaning "made small".

The etymology is quite confusing: A minute is short for "pars minuta prima" where they've omitted "prima" meaning "primary". A "second", which is a part of a part, comes from "pars minuta secunda", where they've omitted "part".

Note how minute and second are also used as angular measurement equal to 1/60 and 1/3600 of a degree respectively. There are 60*360 = 21600 minutes and 60*60*360 = 1296000 seconds in a full rotation.

One sixtieth part of an hour is a minute amount of it. Similarly, one sixtieth part of a minute is a minute amount of a minute. It is of the second order of minuteness (compared to an hour), and is hence called a second.