Meaning

noun the 26th letter of the Roman alphabet

originLikely an alteration of zed (which see for more), by analogy with other letters such as bee, dee, tee and vee. Fell out of usage in England by the 17th century, and made standard in the U.S. in American Dictionary of English Language by Noah Webster in 1828, though usage varied for decades afterwards.

Etymology from Wiktionary, CC BY-SA 3.0