Emily Dickinson Lexicon

CON-TA'GION, n. [L. contagio, from the root of contingo, tango, primarily tago, to touch.]

1. Literally, a touch or touching. Hence, the communication of a disease by contact, or the matter communicated. More generally, that subtil matter which proceeds from a diseased person or body, and communicates the disease to another person; as, in cases of small pox, measles, &c., diseases which are communicated without contact. This contagion proceeds from the breath of the diseased, from the perspiration or other excretions.
2. That which communicates evil from one to another; infection; that which propagates mischief; as, the contagion of vice or of evil examples. – Milton.
3. Pestilence; a pestilential disease; venomous exhalations. – Shak.