cam (n.1) Look up cam at Dictionary.com
"a projecting part of a rotating machinery," 1777, from Dutch cam "cog of a wheel," originally "comb;" cognate of English comb (n.). This might have combined with English camber "having a slight arch;" or the whole thing could be from camber.
cam (n.2) Look up cam at Dictionary.com
abbreviation of camera, by 1990.