On the lam
Definition 1 of 1
Pro Tip 1/3Crime Related
Used specifically when someone is hiding to avoid being caught by the police. 
After the heist, he went on the lam.
Pro Tip 2/3Urgency and Desperation
Implies a sense of urgency or desperation to avoid capture, not a leisurely hiding. 
Desperate to avoid jail, she was on the lam, moving from city to city.
Pro Tip 3/3Cultural Usage
Most commonly used in North American English and often found in crime novels or movies. 
The detective novel described how the thief was on the lam for months.