市
シ, いち, い, ち
market, city, town
JLPT3 G2 S5 F42
The relevant seal inscription form combines 止# (stand straight) and 平 (spread level/flat) → straight line of stalls/shops comprising a *market* → *buying/selling*; *transaction*; *have dealings* → *city* (← place where many gather). There is no etymological connection with 姉.
[Full Kanji Etymology List]