Creepingly
The Century Dictionary and Cyclopedia
By creeping; slowly; with the motion of an insect or a reptile.
the GNU version of the Collaborative International Dictionary of English
adverb.
by creeping slowly; in the manner of a reptile; insidiously; cunningly.
Wiktionary, Creative Commons Attribution/Share-Alike License
adverb.
By
creeping
, moving stealthily and slowly;
insidiously
;
cunningly
.