Where does “proslaveryism” come from?

proslaveryism (English) comes from English slavery, from English slaver, from English slave, from Middle English sclave, from French esclave, from Medieval Latin sclavus, from Ancient Greek Σκλάβος, from Ancient Greek Σκλαβηνός — to cover; to incline.

Ancestry of “proslaveryism”, step by step

StepLanguageWordMeaning
1EnglishslaveryAn institution or social practice of owning human...
2EnglishslaverTo drool saliva from the mouth; to slobber; To...
3EnglishslaveA person who is held in servitude as the property...
4Middle Englishsclaveslave individual held in slavery
5Frenchesclaveslave
6Medieval LatinsclavusSlav, slave; slave
7Ancient GreekΣκλάβοςSlav
8Ancient GreekΣκλαβηνόςSlavic
9Proto-SlavicslověninъSlav
10Proto-Slavicslovoword
11Proto-Balto-Slavicślawas
12Proto-Indo-Europeanḱléwosfame
13Proto-Indo-Europeanḱlew-to hear
14Proto-Indo-Europeanḱel-to cover; to incline
Every word from Proto-Indo-European ḱel-Every word from Proto-Indo-European ḱlew-Every word from Proto-Indo-European ḱléwos