umbrage
  Offense; resentment.  Affording shade.  Vague or indistinct indication; a
  hint.

Uva Ursi
  Common bearberry; a procumbent (trailing along the ground but not
  rooting) evergreen shrub 10-30 cm high with red berries.

Valerianate (Valerianic)
  One of three metameric acids; the typical one (called also inactive
  valeric acid), C4H9co2H, is from valerian root and other sources; it is
  a corrosive, oily liquid, with a strong acid taste, and the odor of old
  cheese.

valvular
  Resembling or functioning as a valve.  Relating to a valve, especially of
  the heart.

varioloid
  Mild form of smallpox occurring in people previously vaccinated or who
  previously had the disease.

vegetable marrow
  Squash plants with elongated fruit and smooth dark green skin and
  whitish flesh.

veratrum
  Poisonous alkaloid from the root hellebore (Veratrum) and from sabadilla
  seeds.  Used externally to treat neuralgia and rheumatism.

verdigris
  Blue or green powder, basic cupric acetate used as a paint pigment and
  fungicide.  A green patina of copper sulfate or copper chloride on
  copper, brass, and bronze exposed to air or seawater.

vermifuge
  Medicine that expels intestinal worms.

vervain (verbena)
  New World plants of the genus Verbena, especially those with showy
  spikes of variously colored flowers.

Vichy water
  Sparkling mineral water from springs at Vichy, France or water similar
  to it.

vis-a-vis
  One that is face to face with or opposite to another.

vitiate
  Reduce the value; impair the quality; corrupt morally; debase; make
  ineffective; invalidate.

voile
  Light, plain-weave, sheer fabric of cotton, rayon, silk, or wool used
  for dresses and curtains.

wahoo
  Shrubby North American tree of the genus Euonymus (E. atropurpureus)
  having a root bark with cathartic properties.

Waldorf salad
  Diced raw apples, celery, and walnuts mixed with mayonnaise.

wen
  Harmless cyst, usually on the scalp or face, containing the fatty
  secretion of a sebaceous gland.

whortleberry
  Two deciduous shrubs, Vaccinium myrtillus, of Eurasia, or V. corymbosum,
  of eastern North America, having edible blackish berries.

wontedness
  Being accustomed.

yarrow
  Plants of the genus Achillea, especially A. millefolium, native to
  Eurasia.  Also called achillea, milfoil.

yellow fever (yellow jack)
  Infectious tropical disease caused by an arbovirus transmitted by
  mosquitoes of the genera Aedes, especially A. aegypti, and Haemagogus;
  it causes high fever, jaundice, and gastrointestinal hemorrhaging.

yerba reuma
  A low California undershrub (Frankenia grandifolia).