The Etymology of Frequency
'Frequency' started as a word for a crowd. Latin 'frequentia' meant a large gathering or multitude, from 'frequens' (crowded, numerous). English borrowed it in 1553, initially using it in the social sense — the frequency of a place was how packed it was. The physics meaning developed in the 19th century as wave theory matured: instead of many people in one space, frequency described many cycles in one second. The metaphor was so natural that the transition happened without anyone remarking on it. The ultimate origin of Latin 'frequens' is debated — one theory connects it to a root meaning 'to stuff' or 'to cram,' which would make the word's core meaning the sensation of being overfull, whether with people or with oscillations.