1An adverb meaning 'not always' or 'not necessarily,' typically paired with a negative predicate — used in the pattern 「必ずしも〜ない」.
高いものが必ずしも良いとは限らない。
Expensive things are not necessarily good.
彼の話は必ずしも事実とは言えない。
His story cannot necessarily be said to be true.
お金があれば必ずしも幸せだとは限らない。
Having money doesn't necessarily mean you're happy.