desire

To desire is, on the oldest reading, to want what the stars hold. Latin desiderare looks like de- and sidus, "star" — the phrase de sidere, "from the stars" — and the sense that has been built on that decomposition is a longing aimed at the sky: to await what the heavens will bring, to want the way one wishes on a star. It is the mirror of consider, which appears to mean "to observe the stars": where considering is the attention you pay the night sky, desiring is the wanting. The two words would then be the matched halves of one ancient posture — a body under the stars, reading them and reaching for them. Looking up, and longing.

The honest report is that this is a beautiful etymology nobody has proven. Etymonline and Wiktionary both present the star-reading and both hedge it — "perhaps from de sidere," "perhaps related to sidus." De Vaan, the standard modern authority on Latin, weighs alternatives for the verb and commits to none. And a century ago Tucker rejected the star-derivation specifically for desiderare, calling the sidus connection "quite inapplicable" and proposing instead a root meaning "to stretch, extend." Even the sense is unsettled: the gentle gloss "await what the stars will bring" is one reconstruction, "wish upon a shooting star" another, and a tidier story you sometimes hear — that desiderare meant "to stop seeing a star," to lose sight of the light you were steering by — is not how any standard source derives the word. It is a modern folk-elaboration, and an honest entry sets it aside.

Because desire and consider rest on the same claim about sidus, they are bound together in their uncertainty: if the star-etymology is right, they are siblings; if it is wrong, they are two unrelated Latin verbs that happen to look alike. They stand or fall as a pair. And the doubt goes one layer deeper still, because sidus itself — the star — has no agreed origin. The reconstructions point in incompatible directions: "sweat," "achieve a goal," a word borrowed from some lost pre-Latin language, "binding." So the etymology of desire is uncertain twice over: whether the -sider- is a star at all, and, if it is, where the star comes from. Wanting is, fittingly, the word whose object keeps receding as you reach for it.

The clean cousins are few. Sidereal, "of the stars," is the one uncontested sidus-word — the astronomer's adjective, no doubt about it. Desideratum, "a thing desired or needed," is desire's learned Latinate twin, secure at the level of the verb whatever the stars turn out to be. The false friends are the other de- and -sid- words that crowd in by sound. Desist looks like a sibling but is de- plus sistere, "to stand, stop." Reside, resident, sediment carry not sidus ("star") but sedēre ("to sit") — the resident "sits back," the sediment "sits down." Design is de- plus signum, "a mark." Only the stars, if they are stars, tie desire to consider. It is the right shape for a word about longing: that the thing it reaches for should be exactly as far away, and exactly as uncertain, as a star.