Something that’s odious is “hateful”, “disgusting”, or “highly offensive”.
It comes from odium, a noun meaning “intense hatred” or the “quality of being hated”. The word odium goes all the way back to Latin, as in the phrase odium theologicum:
The Latin phrase Odium theologicum, literally meaning "theological hatred", is the name originally given to the often intense anger and hatred generated by disputes over theology. It has also been adopted to describe non-theological disputes of a rancorous nature. (Wikipedia)
Reading about this word made me realize just how many types of hatred we’ve defined. On the bright side, though, we probably have even more words for different types of love.