Definition
A precision cutting tool used to enlarge, smooth, and finish a previously drilled hole to an exact diameter and a fine surface finish. As a verb, to ream is to use this tool to bring a hole to its final specified size.
Plain English
A tool that takes a hole that has already been drilled and trims it out to the exact size needed, leaving the inside walls smooth.
Context Anchor
Seen in aircraft maintenance when fitting bolts, rivets, pins, or other parts into drilled holes.
Derivation
From the Old English 'ryman,' meaning 'to widen' or 'make room.' The aviation usage keeps that original sense — opening a hole up to the size it needs to be.
Why Pilots Care
Creates tight, accurate fits that maintain structural strength and prevent loosening or stress points in the airframe.
Intuition Check
Do not confuse reaming with simply drilling a hole. Drilling makes the hole; reaming finishes an existing hole to a more exact size and smoother shape.
Example Sentence 1
After drilling the hole slightly undersize, the mechanic used a reamer to bring it to the exact diameter needed for the bushing.
Example Sentence 2
The mechanic reamed the spar holes to final size before installing the bolts.