1. [mid–late 19C] any form of financial or commercial transaction [20C+ use is SE] .
2. [late 19C+] (orig. US) an idea, plan, scheme, arrangement, current situation, esp. with the implication of illegality or subterfuge.
3. [late 19C+] the treatment one has received, whether good or bad; thus square deal under square adj.
4. [late 19C+] (orig. US) the situation, the state of affairs, e.g. that’s the deal.
5. (US) a beating.
6. [1910s+] (drugs) a purchase or sale of drugs, esp. cannabis; thus quid deal, one pound’s worth etc.
7. [1920s+] (US) a turn of events, a development.
8. [1940s+] (orig. US, also dealie) an individual or thing.
9. [1950s] one’s concern or business, e.g. that’s my deal, that’s my business.
10. [1990s+] (US campus) a problem, a conflict.
11. see dealer n.
[1970s+] (orig. US) to compromise; to make an arrangement, to make a deal.