Source : Webster's Revised Unabridged Dictionary (1913)

Ecchymosis \Ec`chy*mo"sis\, n.; pl. {Ecchymoses}. [NL., fr. Gr.
   ?, fr. ? to extravasate; ? out of + ? to pour.] (Med.)
   A livid or black and blue spot, produced by the extravasation
   or effusion of blood into the areolar tissue from a
   contusion.

Source : WordNet®

ecchymosis
     n 1: the purple or black-and-blue area resulting from a bruise
     2: the escape of blood from ruptured blood vessels into the
        surrounding tissue to form a purple or black-and-blue spot
        on the skin
     [also: {ecchymoses} (pl)]