The word 'thousandths' is a layered construction built upon the ancient Germanic root for the large cardinal number 'thousand'. This root, þūsend, is itself of uncertain deeper origin, though it may be related to a compound meaning 'swollen hundred'. The addition of the ordinal suffix '-th', a native English feature shared with other Germanic languages, transforms the cardinal number into its sequential or fractional form, 'thousandth'. Finally, the plural '-s' is appended, following standard English grammatical rules, to denote multiple instances of this ordinal or fractional unit. Thus, the word's logic progresses from a specific quantity, to its position in order or its role as a single division, to the plural concept of multiple such divisions.

Structure: thousand (cardinal number) + th (ordinal suffix) + s (plural suffix) thousand: From Old English þūsend, of Germanic origin; the cardinal number representing 10 x 100. th: A suffix of Germanic origin used to form ordinal numbers from cardinal numbers (e.g., fourth, tenth). s: A suffix of Germanic origin, the regular plural marker for nouns in English.