The Collaborative International Dictionary of English v.0.48:

Tights \Tights\, n. pl.
   Close-fitting garments, especially for the lower part of the
   body and the legs.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tights
    n 1: skintight knit hose covering the body from the waist to the
         feet worn by acrobats and dancers and as stockings by women
         and girls [syn: tights, leotards]

The Devil's Dictionary (1881-1906):

TIGHTS, n.  An habiliment of the stage designed to reinforce the
general acclamation of the press agent with a particular publicity.
Public attention was once somewhat diverted from this garment to Miss
Lillian Russell's refusal to wear it, and many were the conjectures as
to her motive, the guess of Miss Pauline Hall showing a high order of
ingenuity and sustained reflection.  It was Miss Hall's belief that
nature had not endowed Miss Russell with beautiful legs.  This theory
was impossible of acceptance by the male understanding, but the
conception of a faulty female leg was of so prodigious originality as
to rank among the most brilliant feats of philosophical speculation!
It is strange that in all the controversy regarding Miss Russell's
aversion to tights no one seems to have thought to ascribe it to what
was known among the ancients as "modesty."  The nature of that
sentiment is now imperfectly understood, and possibly incapable of
exposition with the vocabulary that remains to us.  The study of lost
arts has, however, been recently revived and some of the arts
themselves recovered.  This is an epoch of _renaissances_, and there
is ground for hope that the primitive "blush" may be dragged from its
hiding-place amongst the tombs of antiquity and hissed on to the
stage.