假设
jiǎshè · HSK 7
suppose
假 = false/hypothetical + 设 = set up; you set up a false premise, i.e. you suppose
假 carries the sense of false or borrowed, and 设 means to set up or establish. Together they mean to set up a hypothetical premise, matching the English suppose, assume, or presume. Sounds like jyah-shuh.
假 — person radical 亻 + 叚 (borrow)
假 combines the person radical 亻 with 叚, which originally meant 'to borrow' and provides the sound. The core idea is a person borrowing something, which extended to 'borrowed,' 'not real,' or 'fake.' From there it also developed the meaning 'leave/vacation' (time borrowed away from work).
设 — speech 讠 + hand holding tool 殳
设 combines 讠 (speech) with 殳 (a hand wielding a tool or weapon), suggesting giving orders to set something up. The original sense was to arrange or establish through command, which extended to today's meanings of 'set up,' 'design,' or 'suppose.'