Desiccate has the “honor” of being among the most commonly misspelled words in English. I think the mistaken *dessicate is due in part to people’s memory that the word in question has either two s‘s and one c or two c‘s and one s; add to that the many familiar English verbs that end in -cate, with a single c (e.g. fabricate, lubricate, educate, indicate, domesticate), and you’ve got your common misspelling. Probably the only thing that keeps desiccate from being misspelled more often than it already is is the fact that it’s a fancy word, so the people most prone to misspelling in general will never even use it.
The verb desiccate,whose Spanish cognate is desecar, comes from Latin desiccatus, the past participle of desiccare, created from the prefix de-, used as an intensifier, and siccus ‘dry,’ which Spanish speakers recognize as the ancestor of seco. In addition to desecar, Spanish has the simpler and more common secar, which frequently appears as the reflexive secarse ‘to dry out.’ Corresponding to desecar/desiccate is the abstract noun desecación/desiccation. Spanish also has the abstract nouns sequedad ‘aridity, dryness’ and sequía ‘drought.’ A desecante/desiccant is ‘a substance that absorbs moisture and is therefore used as a drying agent.’ Spanish also has the simpler secante (not to be confused with the unrelated secante/secant of geometry).
© 2014 Steven Schwartzman