Capable of speaking easily
eloquent, articulate, voluble, loquacious, glib, facile, wordy, smooth, copious, talkative, mellifluent, mellifluous, able to speak readily, smooth-spoken, well-spoken, ready in speech, garrulous, effusive, declamatory, verbose, chatty, disputatious, argumentative, vocal, clamorous, cogent, persuasive, silver-tongued, honeyed, blarneying*, blabbery*, having the gift of gab*, fast-talking*.
Antonyms inarticulate, tongue-tied, stammering.