the·ri·ac /ˈθɪəriˌæk/
1. molasses; treacle.
2. a paste formerly used as an antidote to poison, esp. snake venom, made from 60 or 70 different drugs pulverized and mixed with honey.

Also, the·ri·a·ca /θəˈraɪəkə/

[Origin: bef. 1000; < L thériaca antidote to poison < Gk thériak, fem. of thériakós, equiv. to thérí(on) wild beast + –akos -ac; r. ME tiriake, OE tȳriaca < ML, var. of thériaca]

-Related forms
the·ri·a·cal, adjective