antigayism

The story

1. Proto-Indo-European*h₂ent-
2. Proto-Indo-European*h₂énts
3. Proto-Indo-European*h₂énti
4. Ancient Greekᾰ̓ντῐ́ (ăntĭ́)
5. Ancient Greekἀντι- (anti-)
6. Englishanti-
7. Proto-Indo-European*ǵʰengʰ-
8. Proto-Germanic*ganhuz
9. Old Occitangai
10. Old Frenchgai
11. Middle Englishgay
12. Englishgay
13. English todayantigayism

From anti- + gay + -ism.