I owe this one to another website (Taylor Houston’s “10 Words You Literally Didn’t Know You Were Getting Wrong”), but since I’ve already addressed about half of the issues they raised it seems okay to cite the others, with proper attribution.

1. Assent vs. Consent: Both of these are verbs, signifying agreement. When you “assent” to something, though, you do so with positive enthusiasm, whereas “consenting” can be neutral or even reluctant. (Another confusion is between “assent” (agree to eagerly) and “ascent” (climb, as in a mountain).

2. Breach vs. Breech: As a noun, a “breach” is a gap of some kind, either geographical (“once more into the breach, lads!”) or legal (a breach of contract). As a verb, it means “to break open or through” (as in “breaching a fortification”). Meanwhile, “breech” is a specific word defining the part of the back of a body (generally human) located between the legs and the back; that is to say, the butt or ass! (Thus, breeches, often pronounced as “britches,” are the things that cover that ass.) The only time it tends to be used nowadays is in describing a birth (human or other animal) in which the critter is coming out ass-first, and must be turned around in the birth canal. Any more questions?
More