dropped, adj.² — Green’s Dictionary of Slang

dropped adj.²

[the trad. gift by the man of a pendant or drop, bearing his initials]

(US campus) unofficially but dedicatedly engaged to be married.

1975		G. Underwood ‘Razorback Sl.’ in AS L:1/2 58: dropped adj Informally engaged or going together.
1981		Eble Campus Sl. Mar. 2: dropped – going steady.