lurking
lur-king
verb
Remaining hidden, often with a sinister or secretive purpose, waiting to act.
"He was lurking behind the bushes."
adjective
Existing in a hidden or undeveloped state, often suggesting a potential threat or problem.
"There was a lurking suspicion in her mind."
Thesaurus
Synonyms: lurk, skulk, bushwhack, waylay, lie in wait, scupper, ambush, ambuscade, lallygag, mill around, loaf, mill about