Unobtrusive, a.
Not obtrusive; not presuming; modest. -- Un`ob*tru"sive*ly, adv. -- Un`ob*tru"sive*ness, n.
Shades of meaning
Fernald lists unobtrusive only as an antonym, under meddlesome.
He lists it without comment; the entries above explain its neighbors.
Synonyms
none given