Where does “thanksies” come from?

thanksies (English) comes from English thanks, from Middle English thanks, from Old English þancas, from Proto-Germanic þankōs, from Proto-Germanic þankaz, from Proto-Indo-European teng- — to think.

Ancestry of “thanksies”, step by step

thanksies traces back through two separate lines of ancestry.

via English thanks

StepLanguageWordMeaning
1EnglishthanksUsed to express appreciation or gratitude; plural...
2Middle Englishthanks
3Old Englishþancasthanks
4Proto-Germanicþankōs
5Proto-Germanicþankazthought; mind; consideration; remembrance;...
6Proto-Indo-Europeanteng-to think

via English sies

StepLanguageWordMeaning
1EnglishsiesExpressing disgust, disappointment, or annoyance;...
Every word from Proto-Indo-European teng-