the Spanish language

(linguistics) linguistic feature characteristic of a given language (and worthy of some in-depth analysis)

(sociolinguistics) language register

(derogatory) serpent's tongue, tendency to speak maliciously / (derogatory) person with such a tendency, malicious gossip

language school

American Sign Language

French Sign Language

(informal) to give up trying to guess something, e.g. the answer to a riddle

(figuratively) to be a chatterbox, to talk a lot, to be very talkative; to have the gift of the gab / (figuratively) to have a sharp tongue, to be sharp-tongued

(idiomatic) on the tip of one's tongue (known but not quite remembered)