From The Collaborative International Dictionary of English v.0.48 [gcide]:
Improperly \Im*prop"er*ly\, adv.
In an improper manner; not properly; unsuitably;
unbecomingly.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
improperly
adv 1: in an improper way; "he checked whether the wound had
healed improperly" [ant: decent, decently, {in good
order}, properly, right, the right way]