Where does “þin” come from?

þin (Middle English) comes from Old English þīn, from Proto-Germanic *þīn, from Proto-Germanic þīnaz, from Proto-Indo-European téynos, from Proto-Indo-European túh₂ — you, thou.

þin (Middle English): Second-person singular possessive determiner:...

Definitions

Second-person singular possessive determiner:...

Ancestry of “þin”, step by step

Step	Language	Word	Meaning
1	Old English	þīn	your (singular), thine, thy
2	Proto-Germanic	*þīn	—
3	Proto-Germanic	þīnaz	your, yours (thy, thine); 2nd person singular possessive
4	Proto-Indo-European	téynos	thy; thine
5	Proto-Indo-European	túh₂	you, thou

Words derived from “þin”

the
thy
thysen
thissen
netheless
thin
thine
þi
thy
thi
behind the scenes
over-the-counter
get the point
take the point
have the biscuit
break the fourth wall
on the turps
non-over-the-counter

Every word from Proto-Indo-European túh₂ →Every word from Proto-Indo-European téynos →Every word from Proto-Germanic þīnaz →