Where does “tertiary planet” come from?

tertiary planet (English) comes from English planet, from Middle English planete, from Old French planete, from Latin planēta, from Ancient Greek πλανήτης, from Ancient Greek -τής, from Ancient Greek πεῖρα, from Proto-Indo-European per- — passed , crossed.

tertiary planet (English): the third planet; usually counting outwards from the central sun

Definitions

  1. the third planet; usually counting outwards from the central sun

Ancestry of “tertiary planet”, step by step

tertiary planet traces back through two separate lines of ancestry.

via English planet

StepLanguageWordMeaning
1EnglishplanetEach of the seven major bodies which move...
2Middle EnglishplaneteEach of the seven celestial bodies which move...
3Old Frenchplaneteplanet
4Latinplanētaplanet (wandering star)
5Ancient Greekπλανήτηςwanderer, vagabond; planet; a fever that comes in...
6Ancient Greek-τήςAppended to verbs to form agent nouns
7Ancient Greekπεῖραtrial, experiment, attempt
8Proto-Indo-Europeanper-before, in front; first; to go through
9Proto-Indo-Europeanpr̥tóspassed , crossed

via English Tertiary

StepLanguageWordMeaning
1EnglishTertiaryOf or pertaining to the first part of the...
2Latintertiāriuscontaining a third part
3Latintertiusthird, the ordinal number after secundus and...
4Latintrēsthree; 3
5Proto-Italictrēsthree
6Proto-Indo-European*tréyes
Every word from Proto-Indo-European pr̥tós