Wordnet 3.0
NOUN (1)
1. 
 narrow wood or metal or plastic runners used in pairs for gliding over snow; 
VERB (1)
1. 
 move along on skis; 
- Example: "We love to ski the Rockies"- Example: "My children don't ski"
The Collaborative International Dictionary of English v.0.48:
Ski \Ski\ (sk[=e]), n.; pl. skis (sk[=e]z). [Dan. ski; Icel.
   sk[imac][eth] a billet of wood. See Skid.]
   A long, flat, narrow runner made of wood, plastic or metal,
   curved upwards in front, having a fitting allowing it to be
   attached to the foot, and used for gliding or sliding over
   snow. Commonly used in the plural, to designate the pair.
   [Also spelled skee.]
   [Webster 1913 Suppl. +PJC] Skiagraph
The Collaborative International Dictionary of English v.0.48:
Skee \Skee\, n. [Dan. ski; Icel. sk[imac]? a billet of wood. See
   Skid.]
   A long strip of wood, curved upwards in front, used on the
   foot for sliding; now usually spelled ski.
   [1913 Webster]
WordNet (r) 3.0 (2006):
ski
    n 1: narrow wood or metal or plastic runners used in pairs for
         gliding over snow
    v 1: move along on skis; "We love to ski the Rockies"; "My
         children don't ski"
Moby Thesaurus II by Grady Ward, 1.0:
25 Moby Thesaurus words for "ski":
   coast, flit, flow, fly, glide, glissade, ice skates, ice-skate,
   roller skates, roller-skate, sail, sideslip, skate, skateboard,
   skates, skid, skim, sled, sleigh, slide, slip, slither, snowshoes,
   sweep, toboggan
V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):
SKI
       Service Key Identifier (X509v3, RFC 3280)