Hello
early 19th century: variant of earlier hollo ; related to holla.
wiktionary
Hello (first attested in 1826), from holla, hollo (attested 1588). This variant of hallo is often credited to Thomas Edison as a coinage for telephone use, but its appearance in print predates the invention of the telephone by several decades.
Ultimately from a variant of Old English ēalā, such as hēlā, which was used colloquially at the time similarly to how hey and hi are used nowadays. Thus, equivalent to a compound of hey and lo. Used when drawing attention to yourself.
Possibly influenced by Old Saxon halo!, imperative of halōn(“to call, fetch”), used in hailing a ferryman, akin to Old High German hala, hola!, imperative forms of halōn, holōn(“to fetch”). More at hallo.
etymonline
hello (interj.)
greeting between persons meeting, 1848, early references are to the U.S. western frontier (where hello, the house was said to be the usual greeting upon approaching a habitation).
It is an alteration of hallo, itself an alteration of holla, hollo, a shout to attract attention, which seems to go back at least to late 14c. (compare Middle English verb halouen "to shout in the chase," hallouing). OED cites Old High German hala, hola, emphatic imperative of halon, holon "to fetch," "used especially in hailing a ferryman." Fowler in the 1920s listed halloo, hallo, halloa, halloo, hello, hillo, hilloa, holla, holler, hollo, holloa, hollow, hullo, and writes, "The multiplicity of forms is bewildering ...."
Its rise to popularity as a greeting (1880s) coincides with the spread of the telephone, where it won out as the word said in answering, over Alexander Graham Bell's suggestion, ahoy. Central telephone exchange operators were known as hello-girls (1889).
Hello, formerly an Americanism, is now nearly as common as hullo in Britain (Say who you are; do not just say 'hello' is the warning given in our telephone directories) and the Englishman cannot be expected to give up the right to say hello if he likes it better than his native hullo. [H.W. Fowler, "A Dictionary of Modern English Usage," 1926]
