The Collaborative International Dictionary of English v.0.48:
Obtrusive \Ob*tru"sive\, a. Disposed to obtrude; inclined to intrude or thrust one's self or one's opinions upon others, or to enter uninvited; forward; pushing; intrusive. -- Ob*tru"sive*ly, adv. -- Ob*tru"sive*ness, n. [1913 Webster] Not obvious, not obtrusive, but retired. --Milton. [1913 Webster]WordNet (r) 3.0 (2006):
obtrusively adv 1: in an obtrusive manner [ant: unobtrusively]