Sapphic ALWAYS refers to lesbian homosexuality in particular (never male) and also always refers to Fem-Fem lesbianism. Also, very importantly, implies some sort of witchcraft is involved. From Sappho, who was poetess of the Isle of Lesbos (600 BC). Thus, some understanding of Greek mythology is required to truly understand why the word means this.

Also, Sapphic engagements tend to always involve young (29 or younger- usually below 23) and beautiful girls that are untainted and have few, if any tattoos or piercings (unless they are totally attractive and symbolize their witchcraft or their allegiance with the dark side). The may have crazy dyed hair colors like blue if they are otherwise completely young and gorgeous.
Thus, they are definitely not like most real lesbians we are used to seeing, and are in fact, largely mythological. A fat T-primed bull dyke fingering her hairy-legged snagletoed friend named Zoë is absolutely not Sapphic

For some strange and unexplainable reason, (probably cosmic in nature), girls named Nina or Ninah, or any spelling of that name tend to be roommates with Sapphic sluts

Literally of or for Sappho. Lesbian/ism.

a homosexual, usually female