The Myth of the Eskimo Snow Lexicon
A common myth among educated people the world over is the "fact" that certain Eskimo tribes have an extraordinary number of words for "snow". While at first that would seem logical for people who spend their lives staring out at a landscape that is an expanse of unbroken white, it seems that this is in fact something of a linguistic urban legend.
The myth of the overabundance of Eskimo terms for snow can be traced back to a linguist of the early twentieth century, Franz Boas, who apparently noted in 1911 that Eskimos have four root words for snow1. This anecdote fell into the hands of Benjamin Lee Whorf (who was, at the time, an insurance inspector, though he went on to greatness in the field of linguistics). When he exaggerated it a little bit (to seven), people took his word for it, and the myth started to grow, as anyone who's ever seen the factoid about Eskimo snow words in some "Believe It or Not" column can attest. At present, versions of the myth are told in which the Eskimos have as many as forty different words for snow, a full order of magnitude greater than was originally observed.
The Truth
Once the mythology has been dispensed with, counting the actual number of Eskimo snow words seems like it should be an easy task. At the moment, a good conservative estimate would probably be Boas' count of four, though it can likely be embellished, depending on how liberal one wants to be with what one considers equivalent to "snow"2.
1 They are: qana, "falling snow", aput, "snow on ground", piqsirpoq, "drifting snow", and qimuqsuq, "snowdrift".
2 Several linguists make the comparison to English, with its terms like "snow", "sleet", "slush", "frost", "flurry"...you get the idea.