A correspondent from Brazil writes to ask about the origins of the phonetics term schwa, used to identify, for example, the English mid-central vowel sound of unstressed the or the final vowel in sofa, and written with an inverted e.
The unabridged Oxford English Dictionary is very good on this. This establishes the origin in Hebrew grammar, where sheva was the name of the sign placed under a consonant letter to show the absence of a following vowel or, in some positions, the sounding of a neutral vowel. In this sense, there are citations in English from as early as 1582. The term was adopted by 19th-century Germanic philologists to identify similar sounds in Indo-European languages, and the symbol was included in the International Phonetic Alphabet when this was devised in the 1880s. The first OED citation for the word in English is 1895, and subsequent usage spells the word both as schwa and shwa, though the former is much more common.
The etymology seems to be that sheva develops a usage as shva in German, and then becomes spelled as
schwa, and thus arrives in English.