Solution 1:

"Thy" is an English word that means "your" in the second person singular.

English used to have a distinction between singular and plural in the second person, such that we had the following:

  • Singular: thou, thee, thy
  • Plural: ye, you, your

Nowadays, we just have "you" and "your" in place of those six distinct words (which is why in nonstandard English, we have things like "y'all" or "youse" to distinguish 2nd-person plural from 2nd-person singular).

Solution 2:

I believe it's still used in parts of Yorkshire.

  • I me my mine
  • Thou thee thy thine (You you your yours)
  • He him his his
  • She her her hers
  • We us our ours
  • Ye you your yours (You you your yours)
  • They them their theirs

Solution 3:

Basically, it means "your".

If you want more detailed definition, check on the Merriam-Webster site:

archaic : of or relating to thee or thyself especially as possessor or agent or as object of an action —used especially in ecclesiastical or literary language and sometimes by Friends especially among themselves

Solution 4:

Archaic.

From dictionary.com.

thy

–pronoun

the possessive case of thou (used as an attributive adjective before a noun beginning with a consonant sound): thy table.

thou

–pronoun

  1. Archaic (except in some elevated or ecclesiastical prose) . the personal pronoun of the second person singular in the nominative case (used to denote the person or thing addressed): Thou shalt not kill.

Solution 5:

‘Thy’ is an old word meaning ‘your’ that was used for talking or writing to one person.