Source : WordNet®

unnoticeable
     adj 1: not obtrusive or undesirably noticeable; "a quiet,
            unobtrusive life of self-denial" [syn: {unobtrusive}]
            [ant: {obtrusive}]
     2: not noticeable; not drawing attention; "her clothes were
        simple and unnoticeable"- J.G.Cozzens [ant: {noticeable}]
     3: not drawing attention; "an unnoticeable cigarette burn on
        the carpet"; "an obscure flaw" [syn: {obscure}]