精々
せいぜい · seizei · JLPT N3 · adverb
at the most
精 = energy, doubled: even with all your energy, that is the most you get
精 means spirit or energy, and 々 repeats it. The sense is that even putting all your energy in only gets you this far, so せいぜい means at most or at best. It often sets a low ceiling: せいぜい三人, three people at most.
精 — rice 米 + blue/green 青 (phonetic)
A semantic-phonetic compound: 米 (rice) gives the meaning, while 青 supplies the sound. Originally referred to polished, refined rice — grain with the husk removed. The sense broadened to 'refined, pure, essence,' and later 'fine, skilled, spirit.'