lurk

Short definition from Wiktionary

Verb

1. 1
   To remain concealed in order to ambush.
2. 2
   To remain unobserved.
3. 3
   To hang out or wait around a location, preferably without drawing attention to oneself.
4. 4
   To read an Internet forum without posting comments or making one's presence apparent.
5. 5
   To saddle (a person) with an undesirable task or duty.

Noun

1. 1
   The act of lurking.
2. 2
   A swindle.