IPA: /ˌʌndərˈpʌblɪzaɪzd/
KK: /ʌndərˈpʌblɪˌzaɪzd/
Not given enough attention or publicity; not widely known or promoted.
The event was underpublicized, so only a few people showed up.
Underpublicized → It is formed from "under-" (meaning below or insufficiently) and "publicize" (from Latin "publicare", meaning to make public) and the suffix "-ed" (indicating a past action). The word describes something that has not been sufficiently made public or is not widely known.
Think of something that is 'below' the level of being 'made public' — that's why underpublicized means not enough people know about it.
No commonly confused words.