word-forming element used in making adjectives from nouns or adjectives (and sometimes verbs) and meaning "tending to; causing; to a considerable degree," from Old English -sum, identical with som (see some). Cognate with Old Frisian -sum, German -sam, Old Norse -samr; also related to same.
suffix added to numerals meaning "a group of (that number)," as in twosome, from pronoun use of Old English sum "some" (see some). Originally a separate word used with the genitive plural (as in sixa sum "six-some"); the inflection disappeared in Middle English and the pronoun was absorbed. Use of some with a number meaning "approximately" also was in Old English.