1. Happening or existing in small, isolated sections: People who were going to work in the patchy fog on the highway had to be very careful so they wouldn't suddenly run into another car.
2. Inconsistent or not of the same quality throughout; having some parts that are good and some that are bad: Pete's patchy skills in writing didn't help him get accepted by the university when he applied for admittance.

Bettie had a patchier understanding about her brother's illness than her mother.

The new carpenter seemed to have the patchiest skills of any of the other construction workers.