Q: The adjective “special” becomes “especially” when used as an adverb. Why isn’t it “specially”? Have any other words had a similar historical development?
A: Both “special” and “especial” have been adjectives in English for hundreds of years. Likewise, “specially” and “especially” have been adverbs nearly as long.
The words are ultimately derived from specialis, a Latin adjective referring to a particular species or something special as opposed to general, according to the Oxford English Dictionary.
English borrowed “special” from Anglo-Norman, where speciall had the original Latin meaning of something specific. It borrowed “especial” from Old French, where the word had developed a secondary sense of preeminent or important.
In English, “special” is generally preferred in uses related to the original Latin sense, while “especial” is mainly used in the secondary Old French sense.
As the OED explains, “the two forms especial and special differ materially in use; the latter (owing perhaps to its closer relation to the Latin etymon) is preferred in applications arising proximately from the primary sense, while the former is chiefly confined to the derivative sense. The distinction is still more marked in the adverbs especially, specially.”
When the adjective “special,” the oldest of the English terms, appeared in writing in the late 12th century, it meant “having a close or exclusive connection with a specified person, thing, or set; own, particular, individual,” the OED says.
The dictionary’s earliest citation is from Ancrene Riwle, an anonymous guide for monastic women, written sometime before 1200:
“Nule ich naut þet ani seo ow bute leaue habbe of ouwer special meister” (“I do not want anyone to see you unless he has leave of your special master”).
When “especial” showed up in the late 14th century, the OED says, it meant “pre-eminent, exceptionally distinguished,” and now chiefly refers to “feelings, qualities, or attributes.”
The first Oxford example is from Chaucer’s “Tale of Melibeus” in The Canterbury Tales (circa 1386). In this passage, Prudence, the wife of Melibeus, advises him on how to deal with his enemies:
“First schul ye clepe to youre counseil a fewe of youre frendes that ben especial” (“First you shall call to your council a few of your friends that are especial [particularly esteemed]”).
When “specially,” the first of the adverbs, appeared in Middle English, it meant “for a special purpose,” according to the OED. The first Oxford citation is from The Chronicle of Robert of Gloucester, an account of early British history, written sometime before 1300.
In this passage, the King of Germany appeals to King John of England to accept being overruled by the Pope in a dispute over the choice for a new Archbishop of Canterbury:
“Þe king of alimayne sende specialliche inou to king Ion þat he wiþdrowe him of is wou” (“The king of Germany sent [a message] especially to King John to forget his wound”).
When the adverb “especially” showed up a century later, the OED says, it meant “in an especial manner; principally, chiefly.” The earliest example, which we’ve expanded here, is from The Chester Whitsun Plays, circa 1400:
“Sybbell, I praye thee especiallye, / By signe thou woulde me certiffye, / What tyme that lorde so royallye, / To raigne he shal begyne” (“Sibyl, I pray to thee especially to tell me with a sign what time the lord so royally shall begin to reign”).
Getting back to your question, English is a Germanic language that has many borrowings from non-Germanic languages. The major source of these loanwords is Latin, either directly or indirectly by way of French.
And as we’ve noted above, the two etymological sources of “special,” “especial,” “specially,” and “especially” are Latin and French. In other words, they evolved much like many other English words.