the world > relative properties > order > agreement, harmony, or congruity > adaptation or adjustment > [noun] > adjustment for accuracy or smooth operation > that which (3)
A person who or thing which modulates something; (later chiefly) a regulator, a controlling mechanism.
Something which is capable of being adjusted; a means by which something may be adjusted; a control. Cf. adjuster, n.
A means by which something may be adjusted; = adjuster, n. 2.