The Collaborative International Dictionary of English v.0.48:

Com- \Com-\
   A prefix from the Latin preposition cum, signifying with,
   together, in conjunction, very, etc. It is used in the form
   com- before b, m, p, and sometimes f, and by assimilation
   becomes col- before l, cor- before r, and con- before any
   consonant except b, h, l, m, p, r, and w. Before a vowel com-
   becomes co-; also before h, w, and sometimes before other
   consonants.
   [1913 Webster]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

COM
       Computer Output on Microfilm


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

COM
       Continuation of Message


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

COM
       Component Object Model (OLE, OLE2, OCX, ActiveX, MS)