• parallax •
Pronunciation: pæ-rê-læks • Hear it!
Part of Speech: Noun
Meaning: The change of an object's appearance, position, or direction due to the observer's change of position.
Notes: Remember to double the L in this word, not the R. Other than that, you should have no problem with the spelling. The adjective accompanying today's word is parallactic or, rarely, parallactical. The adverb is parallactically.
In Play: Parallactic effects are usually small: "Smartphones correct the tiny parallax error in old photography caused by the displacement on old cameras of the viewfinder and the lens." They are also affected by distance: "The closer an object is to its observer, the easier it is to detect the effect of parallax, so the more distant stars are less affected by parallax than the closer ones."
Word History: English borrowed today's Good Word directly from French parallaxe, which took it from Greek parallaxis "change, alteration". Parallaxis is the action noun from the verb parallassein "to alter, alternate", comprising para- "beside, near; against" + allessein "to change, exchange". Allessein is a verb created from allos "other", a word inherited from PIE al- "beyond", which also went into the making of English else. In Latin it emerged as alter "other (of two)", which English took and converted to a verb. It appears in several other borrowings, such as alternative and alternate. Latin also created uls, ultra "beyond" out of the same PIE word, which English helped itself to along with several derivations from the Latin word for its ulterior and ultimate. (Today's Good Word is yet another gift from one of our long-time sustaining contributors of them, William Hupy.)
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