furtive
definition
attempting to avoid notice or attention usually because of guilt or a belief that discovery would lead to trouble
example
She cast a furtive glance at her phone, worried that her boss would see her checking messages during the meeting.
synonyms
stealthyslysecretive
word origin — from Latin 'furtivus', meaning 'theft' or 'stolen', from 'furtus', the past participle of 'furari', meaning 'to steal'