According to the Oxford English Dictionary, hello is an alteration of hallo, hollo, which came from Old High German "halâ, holâ, emphatic imperative of halôn, holôn to fetch, used especially in hailing a ferryman." It also connects the development of hello to the influence of an earlier form, holla, whose origin is in the French holà (roughly, 'whoa there!', from French là 'there'). As in addition to hello,halloo, hallo, hollo, hullo and (rarely) hillo also exist as variants or related words, the word can be spelt using any of all five vowels.
The use of hello as a telephone greeting has been credited to Thomas Edison; according to one source, he expressed his surprise with a misheard Hullo. Alexander Graham Bell initially used Ahoy (as used on ships) as a telephone greeting. However, in 1877, Edison wrote to T.B.A. David, the president of the Central District and Printing Telegraph Company of Pittsburgh:
By 1889, central telephone exchange operators were known as 'hello-girls' due to the association between the greeting and the telephone.
Hello may be derived from hullo, which the American Merriam-Webster dictionary describes as a "chiefly British variant of hello," and which was originally used as an exclamation to call attention, an expression of surprise, or a greeting. Hullo is found in publications as early as 1803. The word hullo is still in use, with the meaning hello.
Hallo and hollo
Hello is alternatively thought to come from the word hallo (1840) via hollo (also holla, holloa, halloo, halloa). The definition of hollo is to shout or an exclamation originally shouted in a hunt when the quarry was spotted:
Fowler's has it that "hallo" is first recorded "as a shout to call attention" in 1864. It is used by Samuel Taylor Coleridge's famous poem The Rime of the Ancient Mariner written in 1798:
Hallo is also German, Danish, Norwegian, Dutch and Afrikaans for Hello. It is used in the Dutch language as early as 1797 in a letter from Willem Bilderdijk to his sister in law as a remark of astonishment.
Webster's dictionary from 1913 traces the etymology of holloa to the Old English halow and suggests: "Perhaps from ah + lo; compare Anglo Saxon ealā."
According to the American Heritage Dictionary, hallo is a modification of the obsolete holla (stop!), perhaps from Old French hola (ho, ho! + la, there, from Latin illac, that way).The Old English verb, hǽlan (1. wv/t1b 1 to heal, cure, save; greet, salute; gehǽl! Hosanna!), may be the ultimate origin of the word. Hǽlan is likely a cognate of German Heil (meaning complete for things and healthy for beings) and other similar words of Germanic origin. Bill Bryson asserts in his book Mother Tongue that "hello" comes from Old English hál béo þu ("Hale be thou", or "whole be thou", meaning a wish for good health) (see also "goodbye" which is a contraction of "God be with you".