moreover, a long time (radical)
According to the dictionaries I checked this word seems to have the following meanings:
1. and, moreover, also (ex. used in 并且 "combine + also" which means "and")
2. temporary, for the time being, about to, will soon (ex. used in 姑且 "temporarily", 租 "grain + temporary" = "to rent", 姐 "woman + about to" = "older sister", 暂且 "for now", etc.)
My mnemonic to combine these two meanings:
Think of a group of people stacking a tower by COMBINING blocks (meaning #1). It is stable for the time being though will soon fall (meaning #2).