Where does “zweitklassig” come from?

zweitklassig (German) comes from German zweite, from German zwei, from Middle High German zwēne, from Old High German zwēne, from Proto-West Germanic twai-, from Proto-Germanic twai, from Proto-Indo-European dwóh₁ — two.

zweitklassig (German): second-class, second-rate

Definitions

second-class, second-rate

Ancestry of “zweitklassig”, step by step

zweitklassig traces back through two separate lines of ancestry.

via German zweite

Step	Language	Word	Meaning
1	German	zweite	second
2	German	zwei	two
3	Middle High German	zwēne	two
4	Old High German	zwēne	two
5	Proto-West Germanic	twai-	two
6	Proto-Germanic	twai	two
7	Proto-Indo-European	dwóh₁	two

via German klasse

Step	Language	Word	Meaning
1	German	klasse	great, awesome
2	Russian	класс	class
3	Latin	classis	any one of the five divisions into which Servius...
4	Proto-Italic	klāssis	—
5	Proto-Indo-European	kelh₁-	to call, cry, summon

Every word from Proto-Indo-European dwóh₁ →Every word from Proto-Germanic twai →Every word from Proto-West Germanic twai- →