opisthognathous 79p#is 09g4n! 0!s8
adj.
5< Gr opisthen, behind (< IE *opi3: see OB3) + 3GNATHOUS6 having receding jaws, as certain insects

opisthotonus - in terminal stages of tetanus, the back muscles become contracted, reversing normal spinal curvature

thenar
n.
5ModL < Gr < IE base *dhen3, palm of the hand, level place > DEN6
1 the palm of the hand or, sometimes, the sole of the foot
2 the bulge at the base of the thumb
adj.
of a thenar
But I remember seeing it only as referring to the base of the thumb

Opisthenar - back of the hand

opt 79pt8
vi.
5Fr opter < L optare: see OPTION6 to make a choice: often with for
opt out (of) to choose not to be or continue in (some activity, organization, etc.)

I dislike the coomonly see “opt for”. I prefer “choose”.

ordnance - military term, primarily referring to weapons, particularly cannons and artillery

"Orchesis", derived from a Greek word referring to the art of dance,

orchitis ; - inflammation of the testicles

orenda = Traditional Native American song is used to change the life condition of the entire community, and helps to heal maladies of the mind, body, and spirit

orgeat
n.
5Fr < Prov orjat < orge, barley < L hordeum < IE base *Dhrzd, barley > Ger gerste6 a syrup or beverage, orig. made from barley, flavored with almonds and orange flowers

osmagogue - not in dictionary, not found on Internet. Roots suggest it means enhancing ability to smell. Never heard of such an agent.

osphresis
n. sense of smell. osphretic, a.