IPA: /nɒnˈmeɪnstriːm/
KK: /nɑnˈmeɪnˌstrim/
Referring to ideas, styles, or activities that are not widely accepted or popular among the general public.
The film festival showcased many nonmainstream movies that challenged traditional storytelling.
Nonmainstream → It is formed from "non-" (meaning not) and "mainstream" (from Old English "mǣne" meaning common or ordinary, and "stream" meaning a flow or current). The word "nonmainstream" refers to something that is not part of the common or ordinary flow of ideas or trends.
Think of 'not' ('non-') being combined with 'common flow' ('mainstream') to remember that 'nonmainstream' describes something that goes against the usual trends.
No commonly confused words.