Answer:

uptake

Answer	Crossword Clue
UPTAKE	Comprehension
UPTAKE	Mental grasp
UPTAKE	Absorption

UPTAKE	Grasp
UPTAKE	Quick on the ..: smart
UPTAKE	Understanding
UPTAKE	Quick on the ...
UPTAKE	Comprehension.
UPTAKE	Capacity for understanding.
UPTAKE	Understanding: Colloq.
UPTAKE	Understanding.

UPTAKE	Ventilating shaft
UPTAKE	Slow on the ... (thickheaded)
UPTAKE	Slow on the ... (dense)
UPTAKE	Slow on the ...
UPTAKE	The dim are slow on it
UPTAKE	Slow on the ... (not smart)
UPTAKE	Quick on the ... (smart)
UPTAKE	Quick on the ..

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.