Comb, Saw, Wheel, Cog...
…with teeth.
As youâve probably noticed in our list, a lot of our body-related words are used simply because the particular feature of the object resembles the physical form ofâor serves a similar function asâthe body part used to describe it. In this case, the projections of a comb, saw, wheel, or cog loosely resemble human teeth (maybe?), but, to a greater degree, they mimic the actions of the teeth: separating, breaking down, cutting in, and grinding. The size of the teethâand, for saws, wheels, and cogs, the angles at which the teeth are cutâresults in different âseparatingâ abilities and efficiencies.
When we say weâre going over something âwith a fine-tooth comb,â weâre being meticulous in separating the component strands (literal or metaphorical) of whatever weâre looking at.