infectious

UK: ɪnˈfekʃəs | US: ɪnˈfekʃəs

Definition

  1. adj. capable of causing infection

  2. adj. likely to spread or influence others

  3. adj. (of laughter or enthusiasm) irresistible

Structure
in <into>fect <make/do>ious <adjective suffix>
Etymology

Derived from Latin inficere (to stain, corrupt), combining in- (into) + facere (to make/do). The root fect evolved from facere, retaining the core meaning of "acting upon." The suffix -ious (from Latin -iosus) denotes "full of" or "having the quality of." The word originally described diseases "making their way into" the body, later extending metaphorically to ideas or emotions "spreading" similarly.

Examples

  1. Measles is highly infectious.

  2. Her enthusiasm was infectious, energizing the whole team.

  3. The video went viral due to its infectious humor.

  4. Antibiotics treat bacterial but not viral infectious diseases.

  5. His infectious laugh made everyone smile.