fluent /ˈfluːənt/adjective 3noun 1forms 3 adjective3 •That flows; flowing, liquid.For time is a fleeting thing, and which appeareth as in a shadow, with the matter ever gliding, alwaies fluent, without ever being stable or permanent[…]. — 1603 •Able to use a language accurately, rapidly, and confidently.She's fluent in French. •Being or relating to a fluent interface.The payment processor offers a fluent API. noun1 •(no longer used) A continuous variable, especially one with respect to time in Newton's Method of Fluxions. formsfluents · more fluent · most fluent