既
jì · HSK 4
since...then
🍚 Etymology: person turned away from food bowl = finished eating, hence 'already/since'
既 originally showed a person (旡) turning away from a food vessel (皀), meaning the meal is done. From 'already finished' it extended to 'since' as in 'since X, then Y'. Pairs with 又 or 也: 既A又B = both A and B.
既 — 皀 (food vessel) + 旡 (person turning away)
Originally a pictograph of a person turning away from a food vessel, signaling a finished meal. From this came the meanings 'already' and 'completed.' The modern sense 'since' or 'now that' developed by extension from the idea of an action already done.