1. To bind, fasten, or secure something to some surface, typically the ground, with or as with pegs. A noun or pronoun can be used between "peg" and "down." Make sure you peg that tarp down or it will get blown away in the storm. I'm going to get some firewood while you peg down the tent.

2. To force someone to conform to something, such as a standard, a set of rules, a course of action, etc. In this usage, a noun or pronoun is used between "peg" and "down"; typically followed by "to (something.)" We've never been able to peg my brother down to the rules my parents set. He's always just been rebellious and stubborn like that. Anyone trying to peg the him down to a logical, consistent ideology is on a fool's errand. I know the artist doesn't like being pegged down to any one genre or style.

3. To force someone to conform to something, such as a standard, a set of rules, a course of action, etc. In this usage, a noun or pronoun is used between "peg" and "down"; typically followed by "as (something.)" I pegged her down as a total bore when she first started working here, but since getting to know her, she's actually pretty interesting. I'm disappointed, Jake—I never pegged you down as a quitter.