The term 'quick on the uptake' is often used to describe someone who is able to understand and learn quickly. This can be seen in the crossword solutions for the term, which include AGILE (5 letters), SHAR (4 letters), ALERT (5 letters), INTELLIGENT (11 letters), BRAINY (6 letters), SMART (5 letters), SHARP (5 letters), KEEN (4 letters), ASTUTE (6 letters), and APT (3 letters). All of these words are synonyms for quick-wittedness and intelligence, suggesting that the person being described is able to think and act quickly.