A lot vs. Alot: 9 Grammatical Pitfalls
"person engaged in innovative research," especially in aviation, 1945; earlier "elderly naval officer" (1941), probably from one of the "Mr. Boffins" of English literature (e.g. "Our Mutual Friend").
Very remarkable, awful, admirable, distressing, etc; a HELL OF A, some kind of: Getting the thing together was a bitch of a job/ She's wearing one sweet bitch of a dress! (1960s+)