Definition of ESTRUS. : a regularly recurrent state of sexual excitability during which the female of most mammals will accept the male and is capable of conceiving: heat; also: a single occurrence of this state. See estrus defined for kids.
1. (medicine) any of various liquids sold as medicine (as by a travelling medicine show) but medically worthless. 2. communication (written or spoken) intended to deceive. Familiarity information: SNAKE OIL used as a noun is rare. Dictionary entry details.
The prophesy of the Snake biting man's heel, but man crushing the Snake's head, is taken to refer to Jesus Christ's victory over the devil (and sin) on the cross. As a result, most symbolic meanings of the Snake are in a derogatory sense, both in traditional Chinese culture and Western culture. However, it's not always the case, and some symbolic meanings of the Snake are commendatory.