Green’s Dictionary of Slang

1. (US teen gang) a female gang-member.

1971		E.E. Landy Underground Dict. (1972) 163: ruca (Spanish) n. Girl.
1993		L. Rodríguez Always Running (1996) 62: We invited rucas [...] the Acuña sisters.

2. (US prison) an inmate’s wife or girlfriend.

1992		Bentley & Corbett Prison Sl. 53: Mi Ruca A convict’s wife or girlfriend. The English equivalent is ‘old lady.’.
1995		R. Ramos ‘An Ethnographic Study of Heroin Abuse by Mexican Americans in San Antonio, Texas’ on Texas Commission on Alcohol and Drug Abuse 🌐 ‘Appendix A: Gloss. of Tecato Argot’ Ruca – Woman/wife or girlfriend. Ruco – Guy/‘old man’/husband/boyfriend.
2000		Other Side of the Wall: Prisoner’s Dict. July 🌐 Ruca(o): Old Lady or Old Man ... as in, ‘She/he is my ...’ (Sp.).
2019		D. Winslow Border [ebook] [Y]ou sure as shit didn’t disrespect his ruca or his girlfriend [...] and when you got out, you didn’t mess with a member’s woman.