1.
at most, at best
Indicating the upper limit of what can be expected; no more than.
精々100人ぐらいだろう。
It's probably 100 people at most.
私にできるのは精々これくらいだ。
This is about all I can do.
今の給料では、精々月に一回外食できるくらいだ。
With my current salary, I can eat out at most about once a month.
2.
as much as possible, to the best of one's ability
Doing something with maximum effort (often with slight resignation or irony).
精々頑張ってください。
Do your best (as much as you can).
Can sound slightly dismissive depending on context
時間があるなら、精々楽しんでこい。
If you have time, enjoy yourself as much as you can.
残り少ない休みなんだから、精々ゆっくり休んでおいたほうがいい。
You don't have much vacation left, so you'd better rest as much as you can while you have the chance.
精々 is an adverb with two main nuances: setting an upper limit ("at most") and doing one's best (sometimes with an ironic edge).
MEANING 1 - UPPER LIMIT:
Sets a ceiling, implying the actual amount is less than expected.
- 精々100人くらい: at most about 100 people
- 精々3日: at most 3 days
MEANING 2 - ENCOURAGEMENT/IRONY:
When used to mean "do your best," it often carries a slightly dismissive or ironic tone, depending on context.
- 精々頑張ってください: good luck with that / do your best (can sound sarcastic)
WRITING:
Usually written in hiragana (せいぜい). The kanji 精々 is uncommon.
CONTRAST:
- 精々: at most (upper limit)
- 少なくとも: at least (lower limit)
- せめて: at least (expresses a wish for a minimum)
Related Words
Contrast:
少なくとも (at least)