A hunch meaning a presentiment or positive feeling that something or other will be the case is American and dates from the early 20th century. How this meaning came about is interesting. Originally, from the late 16th century, hunch was a verb meaning to push or shove but its etymology is unknown. Soon thereafter, it evolved into meaning to push or shove into a hump from which the word hunchback derived by the early 1700s. By the mid-19th century, in America, a figurative sense meaning a tip or shove towards a solution had evolved and it was this meaning that eventually evolved into the current meaning by the early 20th century.