sub-

sub- pref. repr. L. sub-, the prep. SUB1 under, close to, up to, towards, used in comps. The full form is retained before vowels and b, d, l, n, s, t; the b is assimilated to c, f, g, p, and often to m and r. A by-form subs- was normally reduced to sus- in comps, with initial c, p, t. As a living prefix it is used with words of any orig.

It is used with the foll. senses:
1. under, underneath, below, at the bottom (of), as subaqueous, subterranean;

2. subordinate, subsidiary, secondary, esp. in titles, as subdeacon;

3. (math.) expressing a ratio the inverse of that of the radical element, as in submultiple, subtriple;

4. next below or after, near or close (to), as in subsequent, suburb;

5. incomplete(ly), imperfect(ly), partial(ly), as in subcylindrical, subtriangular;

6. secretly, covertly, as in suborn;

7. from below, up, (hence) away, as in succour, suspicion;

8. in place of another, as in substitute;

9. in addition, as in subjoin.