Noah Webster's New International Dictionary of the English Language

1. (n.) The act or process of infecting.

2. (n.) That which infects, or causes the communicated disease; any effluvium, miasm, or pestilential matter by which an infectious disease is caused.

3. (n.) The state of being infected; contamination by morbific particles; the result of infecting influence; a prevailing disease; epidemic.

4. (n.) That which taints or corrupts morally; as, the infection of vicious principles.

5. (n.) Contamination by illegality, as in cases of contraband goods; implication.

6. (n.) Sympathetic communication of like qualities or emotions; influence.