IPA: /ˈbɔːrsəm/
KK: /ˈbɔːrsəm/
Something that is dull and fails to hold interest or attention.
The movie was so boresome that I fell asleep halfway through.
Comparative: more boresome
Superlative: most boresome
Boresome → It is formed from "bore" (from Old English "borian", meaning to pierce or drill) and "-some" (meaning characterized by or causing). The word "boresome" means characterized by causing boredom or weariness.
Think of something that 'pierces' your interest and makes you feel 'weary' — that's why boresome means something that causes boredom.