suffix
[Sense: 1; Origin:Old English -sum]
[Sense: 2; Origin: some]
[in adjectives]
tending to behave in a particular way, or having a particular quality
　a troublesome boy (=who causes trouble)
　a bothersome back injury (=that bothers you)
[in nouns]
a group of a particular number, for example in a game
　a golf foursome (=four people playing golf together)