Words I Don't Know: And the nerd goes on.

detente (n.):  a relaxing of tension, esp. between nations, as by negotiations or agreements.
purveyor (n.):  a person or thing that habitually provides or supplies a particular thing or quality.
replete (adj.):  stuffed or gorged with food and drink.
triage (n.):  the determination of priorities for action in an emergency.
dendritic (adj.):  of a branching form.
anterior (adj.):  pertaining to or toward the front plane of the body, equivalent to the ventral surface of quadrupeds.
hypothalamus (n.):  a region of the brain, between the thalamus and the midbrain, that functions as the main control center for the autonomic nervous system by regulating sleep cycles, body temperature, appetite, etc., and that acts as an endocrine gland by producing hormones, including the releasing factors that control the hormonal secretions of the pituitary gland. 
aficionado (n.):  an ardent devotee; fan, enthusiast.

exigency (n.):  a case or situation that demands prompt action or remedy; emergency.
exculpatory (adj.):  tending to clear from a charge of fault or guilt.
interdental (adj.):  situated between teeth.
fricative (adj.):  characterized by audible friction produced by forcing the breath through a constricted or partially obstructed passage in the vocal tract; spirantal; spirant.
sibilant (adj.):  characterized by a hissing sound.
ex tempore (adv.):  without preparation.
profundity (n.):  the quality or state of being profound; depth.
pianissimo (adv.):  very softly.
craven (adj.):  cowardly; contemptibly timid; pusillanimous*
axiom (n.):  a self-evident truth that requires no proof; a universally accepted principle or rule.
braggadocio (n.):  empty boasting; bragging.
ballast (v.):  to give steadiness to; keep steady.
vaccaphobia (n.):  fear of cows.
cantilever (n.):  A projecting structure, such as a beam, that is supported at one end and that carries a load at the other end or along its length.
epidemiology (n.):  the branch of medicine dealing with the incidence and prevalence of disease in large populations and with detection of the source and cause of epidemics of infectious disease. 
impetigo (n.):  a contagious skin disease, esp. of children, usually caused by streptococcal bacteria, marked by a superficial pustular eruption, particularly on the face.
pithy (adj.):  brief, forceful, and meaningful in expression; full of vigor, substance, or meaning; terse;  forcible.
simian (adj.):  of or pertaining to an ape or monkey.
bacchanal (n.):  a drunken and riotous celebration.
kibitz (v.):  to offer advice or criticism to as a kibitzer (busybody).
zaftig (adj.):  full-bodied; well-proportioned.
 

*Look, a former WIDK!
definitions from dictionary.reference.com