crackerjack

The late 19th-century pairing of crack and jack to form crackerjack topped off a long history for those words. Cracker is an elongation of crack, an adjective meaning "expert" or "superior" that dates from the 18th century. Prior to that, crack was a noun meaning "something superior" and a verb meaning "to boast." (The verb use evolved from the expression "to crack a boast," which came from the sense of crack meaning "to make a loud sharp sound.") Jack has been used for "man" since the mid-1500s, as in "jack-of-all-trades." Crackerjack entered English first as a noun referring to "a person or thing of marked excellence," then as an adjective. You may also know Cracker Jack as a snack of candied popcorn and peanuts. That trademarked name dates from the 1890s.