effusive /(?)/

ef·fu·sive

effusive

a.
  1. Pouring out; pouring forth freely. [archaic]
  2. formed by an outpouring of molten lava, or pertaining to rocks so formed. (Geol.)
  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.

Phrases & Compounds
Effusive rocks
volcanic rocks formed by a nonexplosive outpouring of lava in molten or plastic form; in distinction from so-called intrusive, or plutonic, rocks.