sub-, suc-, suf-, sug-, sum-, sup-, sur-, sus-, su-

Don't confuse the sur- in this element with the sur- in super-. Note: sub- regularly means "under", but it often changes its form as it retains or keeps its meaning:

The prefix sub- often becomes suc- before c: succumb.

The prefix sub- often becomes suf- before f: suffuse.

The prefix sub- often becomes sug- before g: suggest.

The prefix sub- often becomes sum- before m: sumptuous.

The prefix sub- often becomes sup- before p: suppression.

The prefix sub- often becomes sur- before r: surrogate.

The prefix, sub- is often simplified to su- before sp; as seen in suspect, suspend, suspicion, suspension, et al. Before c, p, and t; it is sometimes formed into sus-.