The phrase “musical chops” falls into a category of loosely specified lingo that musicians use when referring to several fundamental musicianship skills. A musician might impress his colleagues and receive compliments on his “chops,” which translates to his ability to play. The word most commonly is used by itself, although, in some cases the entire phrase may be used. There are four instances in which this word or phrase commonly appears.
A performer able to perform on his instrument with great flexibility has musical chops. It means he has developed to perform passages with great ease and agility. For a wind player it means he can easily slur wide passages. Slurring is a technique that requires playing without any articulations. Slurring a passage for a wind player is often more difficult than playing with articulations.
Another instance where a performer may receive a compliment on his musical chops is when performing a difficult, fast-paced passage with ease. Performing anything at a high rate of speed on an instrument is difficult, performing it accurately shows that you have excellent chops. This applies to any instrumentalist and refers to the basic ability to play technical music on their instrument.
High notes are difficult on most any instrument, except for keyboard and percussion instruments. Playing high notes on a brass instrument requires strong chops that equates to a strong embouchure and breath support. Playing high notes on a woodwind instrument requires adequate air support and the ability to play without squeaking. String instruments are difficult since the higher a pitch is, the more cramped the finger position becomes. Playing high notes accurately on a string instrument also requires a good deal of chops.
Finally, chops can refer to general overall musicianship and proficiency. A player that consistently plays over the course of several performances at a high level has good and reliable chops. "Chops" in this sense refers to a general ability to play music in a professional manner without making mistakes, forgetting music, arriving late or causing problems with a performance group.