Yes, 'com-' is a prefix. Check words like:
The prefix for combustion is "com-".
The prefix of "compress" is "com-".
The prefix for "compensate" is "com-".
The prefix for complementary is "com-".
The prefix of "complicate" is "com-".
The prefix for combustion is "com-".
The prefix of "compress" is "com-".
The prefix for "compensate" is "com-".
The prefix for complementary is "com-".
The prefix of "complicate" is "com-".
The prefix for the word "Complicate" is "Com".
Com
"with"
The prefix for compassion is "com-" which means "together" or "with."
The prefix of commercial is "com-" which means "together" or "with."
The prefix of the word comprehensible is "com-".
Com- and con- are prefixes that mean "together"or "with."