You can use a biblical hebrew dictionary, BDB(Brown Driver Briggs) is a classic. You can use a concordance. Strongs concordance(a concordance lists all occurrences of a word - and strongs has english translation). They are written by Christians, but not missionaries. Academically rigorous scholars. Modern Orthodox Jews if they are scholarly and very into hebrew grammar, will use them too because they are so good.
Writers of biblical hebrew dictionaries work it out with a biblical concordance. You can use software like BibleWorks too, to look up all occurrences of a word to see it used in lots of contexts to determine if there is a general meaning or general meaning(s).
Strongs concordance labels the word H5769 That link might combine BDB and Strongs.. or maybe just one of them. It is classifying and defining every usage of the word.
ever (272x), everlasting (63x), old (22x), perpetual (22x), evermore (15x), never (13x), time (6x), ancient (5x), world (4x), always (3x), alway (2x), long (2x), more (2x), never (with H408) (2x), misc (6x).
I wanted to see what the miscellaneous usages were but they that one is a broken link.
You can go to that link above and click 'world' on that H5769(olam) page and it lists many passages where it means world.
But mostly it means forever.