not always; not necessarily; not entirely
Always used with a negative predicate (ない, とは限らない, etc.) to express that something is not universally true or does not always hold.
高いものが必ずしも良いとは限らない。
Expensive things are not necessarily good.
What he says is not always correct.
Expensive wine isn't necessarily delicious.
You can't necessarily say his opinion is correct.
More isn't always better.