to perform music or some other entertainment in the street or other public place for voluntary donations
To busk is from the obsolete French verb busquer, thus defined by Randle Cotgrave in A Dictionarie of the French and English Tongues (1611):
Busquer. To shift, filtch; prowle, catch by hook or crook.
Busquer fortune. To go seeke his fortune.
According to the first edition (1694) of the Dictionnaire de L’Académie française, the verb was only used in the phrase busquer fortune, meaning to seek one’s fortune.
This French verb is from Spanish buscar, to seek out, to procure, which must have originally meant to look for, and to collect, firewood, as it is from an unattested Vulgar Latin noun buskum, which is also the origin of the French noun bûche, meaning log. English words such as bush and ambush are ultimately related to this Vulgar Latin noun of Germanic origin.
The English verb to busk originally meant to go searching for something. It is first recorded in The triumphs of Gods revenge against the crying and execrable sinne of (willfull and premeditated) murther (1635), by John Reynolds (floruit 1621-50):
Some three or foure expert Swimmers [...] speed away to the pond; wherein after those Swimmers had beene a quarter of an houre, and curiously busked and dived in most places thereof to find out this cloath, [...] one of them diving far better than the rest, sees and finds it, and swimming with his left hand, brings it a shore in his right hand.
Similarly, in The plain-dealer a comedy (1677), the English playwright William Wycherley (1640-1716) wrote:
Thou art a handsom Spaniel, and canst faun [= fawn] naturally; go, busk about, and run thy self into the next great Man’s Lobby: first faun upon the Slaves without, and then run into the Ladies Bed-chamber; thou may’st be admitted, at last, to tumble her Bed: go, seek, I say.
The current sense of to busk is first attested in A General History of the Science and Practice of Music (1776), by John Hawkins (1719-89), music scholar and lawyer. The author quotes the following account of a musician named Thomas Eccles:
It was about the month of November, in the year 1735, that I with some friends were met to spend the evening at a tavern in the city, when this man, in a mean but decent garb, was introduced to us by the waiter; immediately upon opening the door I heard the twang of one of his strings from under his coat, which was accompanied with the question, “Gentlemen will you please to hear any music?” [...] He was idle, and given to drinking. He lodged in the Butcher-row near Temple bar, and was well-known to the musicians of his time, who thought themselves disgraced by this practice of his, for which they have a term of reproach not very intelligible; they call it going a-busking.
Apparently from jazz slang, to busk also means to improvise, to speak or write without preparation, especially in to busk it. For example, in Revelations; I delivered my speech – and a shower of saliva in their laps, published in The Independent of 15th June 1998, Stephen Poliakoff (born 1952), British playwright, director and scriptwriter, wrote:
The next year, 1968, the school put on Billy Budd and we all applied to be in it. [...] I can still see myself walking towards the noticeboard, behind one of those dreadful glass cases which only seem to exist in schools, and where the final cast was pinned up. It felt far worse than getting any exam result. I scanned the list several times but my name was nowhere to be seen. So in vengeful mood I founded a theatre magazine, to review shows and movies around town, but with the express intention of butchering this production. I gave it a very camp name, for reasons I can’t now remember, Aubrey and Melissa. I did most of the writing and – busking it – even reviewed things I hadn’t seen!