The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with on the uptake
In understanding or comprehension. This term is most often put as
quick on the uptake, for readily understanding something, and
slow on the uptake, for being slow to comprehend. For example, Shirley will have no trouble learning that new computer program—she's very quick on the uptake. It alludes to absorbing (“taking up”) information.
[ Early 1800s