de·sert2 (d-zûrt) KEY
Middle English, from Old French deserte, from feminine past participle of deservir, to deserve ; see deserve
When Shakespeare says in Sonnet 72, "Unless you would devise some virtuous lie,/To do more for me than mine own desert," he is using the word desert in the sense of "worthiness; deserving," a word perhaps most familiar to us in the plural, meaning "something that is deserved," as in the phrase just deserts. This word goes back to the Latin word dservre, "to devote oneself to the service of," which in Vulgar Latin came to mean "to merit by service." Dservre is made up of d-, meaning "thoroughly," and servre, "to serve." Knowing this, we can distinguish this desert from desert, "a wasteland," and desert, "to abandon," both of which go back to Latin dserere, "to forsake, leave uninhabited," which is made up of d-, expressing the notion of undoing, and the verb serere, "to link together." We can also distinguish all three deserts from dessert, "a sweet course at the end of a meal," which is from the French word desservir, "to clear the table." Desservir is made up of des-, expressing the notion of reversal, and servir (from Latin servre), "to serve," hence, "to unserve" or "to clear the table."