The word "onescore" is spelled as /wʌn skɔːr/ in IPA phonetic transcription. This word originally meant "one twenty", but it is now rarely used in modern English. The spelling of "onescore" is a combination of the words "one" and "score", with "score" meaning twenty. The pronunciation of this word is often difficult for non-native English speakers, as it includes the schwa sound /ə/, which is commonly used in unstressed syllables in English.
The word onescore is a compound of two Old English words: one and score. One is derived from the Proto-Germanic word ainaz, meaning one or single. Score comes from the Old Norse word skor, meaning a notch or a tally.
In Old English, score specifically referred to a tally of twenty, which was made by notching a piece of wood or bone. Therefore, onescore originally meant one twenty or twenty. Over time, the word evolved to generally represent the number twenty or any multiple thereof. However, in modern usage, onescore is rarely used and has largely been replaced by twenty.