Use 'skulk' to describe someone moving with stealth, avoiding being seen, often for a nefarious reason. Thieves tend to skulk through dark alleys at night.
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Negative Connotation
'Skulk' often implies a sense of guilt or wrongdoing associated with the sneaking action. After the argument, he skulked away without apologizing.
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Subtle Suspicion
It can hint at someone being up to something suspicious or dishonest. Why are you skulking around my desk? Are you hiding something?