a. 1. Pouring out; pouring forth freely. [ archaic ] “Washed with the effusive wave.” Pope. [ 1913 Webster ]
2. (Geol.) formed by an outpouring of molten lava, or pertaining to rocks so formed. [ PJC ]
3. overly demonstrative; expressing emotion in an unrestrained manner; exhibiting unrestrained enthusiasm; -- of people and human actions; as, effusive thanks; an effusive letter of recommendation. Contrasted with reserved. [ wns=1+2 ]
Syn. -- gushing, gushy, burbling, burbly. [ PJC ]
Effusive rocks (Geol.), volcanic rocks formed by a nonexplosive outpouring of lava in molten or plastic form; in distinction from so-called intrusive, or plutonic, rocks.
-- Ef*fu"sive*ly, adv. -- Ef*fu"sive*ness, n. [ 1913 Webster ]