The Collaborative International Dictionary of English v.0.48:

Taut \Taut\, a. [Dan. t[ae]t; akin to E. tight. See Tight.]
   1. (Naut.) Tight; stretched; not slack; -- said esp. of a
      rope that is tightly strained.
      [1913 Webster]

   2. Snug; close; firm; secure.
      [1913 Webster]

   Taut hand (Naut.), a sailor's term for an officer who is
      severe in discipline.
      [1913 Webster]

WordNet (r) 3.0 (2006):

taut
    adj 1: pulled or drawn tight; "taut sails"; "a tight drumhead";
           "a tight rope" [syn: taut, tight]
    2: subjected to great tension; stretched tight; "the skin of his
       face looked drawn and tight"; "her nerves were taut as the
       strings of a bow"

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "taut":
   all ataunto, anxious, apprehensive, ataunt, bungup and bilge-free,
   close, dragged out, drawn, drawn out, elongated, extended, firm,
   in suspense, in trim, keyed-up, lengthened, neat, on edge,
   on tenterhooks, on tiptoe, orderly, pokerlike, prolongated,
   prolonged, protracted, pulled, quivering, ramrodlike, renitent,
   rigid, rodlike, shipshape, smart, spruce, spun out, starched,
   starchy, stiff, stiff as buckram, straggling, strained, stretched,
   stretched out, stretched tight, strung out, tense, tidy, tight,
   trig, trim, under a strain, unrelaxed, uptight, virgate,
   with bated breath, with muscles tense