Source : Webster's Revised Unabridged Dictionary (1913)

Extravasate \Ex*trav"a*sate\, v. i. [See {Extravasate}, v. t.]
   (Physiol.)
   To pass by infiltration or effusion from the normal channel,
   such as a blood vessel or a lymphatic, into the surrounding
   tissue; -- said of blood, lymph, etc.

Extravasate \Ex*trav"a*sate\, v. t. [imp. & p. p.
   {Extravasated}; p. pr. & vb. n. {Extravasating}.] [Pref.
   extra- + L. vas vessel: cf. F. extravaser. See {Vase}.]
   To force or let out of the proper vessels or arteries, as
   blood.

Source : WordNet®

extravasate
     v 1: force out or cause to escape from a proper vessel or channel
     2: become active and spew forth lava and rocks; "Vesuvius
        erupts once in a while" [syn: {erupt}, {belch}]
     3: geology: cause molten material, such as lava, to pour forth