If you sweat you're a perspirator, not a perspirantor -- a sweater, not a sweanter -- but you still use an antiperspirant against sweating. See how "sweating" a

If you sweat you're a perspirator, not a perspirantor -- a sweater, not a sweanter -- but you still use an antiperspirant against sweating. See how "sweating" also has an 'n' in it, but "sweater" doesn't? The -ant is just the French version of -ing.