The Collaborative International Dictionary of English v.0.48:

Skirmish \Skir"mish\, v. i. [imp. & p. p. Skirmished; p. pr. &
   vb. n. Skirmishing.] [OE. skirmishen, scarmishen, OF.
   escremir, eskermir, to fence, fight, F. escrimer, of German
   origin; cf. OHG. scirmen to protect, defend, G. schirmen,
   OHG. scirm, scerm, protection, shield, G. schirm; perhaps
   akin to Gr. ???? a sunshade. Cf. Scaramouch, Scrimmage.]
   To fight slightly or in small parties; to engage in a
   skirmish or skirmishes; to act as skirmishers.
   [1913 Webster]