It's really not. If you're just reading it as depending on each other, then that can be normal and healthy, but that's not what people usually mean when they say "codependent." Codependency describes a series of unhealthy, maladaptive compulsions developed by those in long-lasting family relationships which are under constant stress (from chemical dependence, poor mental health, abuse, etc.).
A need to control every situation, a tendency to martyr one's self in order to solve a problem, creating personal emotional crisis as an attention seeking device, and compulsively seeking out unhealthy relationships even after the original unhealthy relationship has ended are all compulsions relating to codependency.