Theirs

Part of speech: pronoun

Pronunciation: /ðɛəz/

Definitions

1. Pertaining to the possessions or attributes that are associated with a specific group or individuals
2. Referring to the belongings or rights that relate to certain persons or entities
3. Belonging to or associated with them as owners or possessors

Etymology: English once had a longer possessive for "they" that sounded more like "mine" and "thine." The older form was "theirn," built on the same pattern as those words, and it survived in some dialects long after the standard language had moved on. "Theirs" arrived in Middle English, attested from the 1300s, and it is simply "their" with the "-s" ending that also marks "his" and the possessive "'s." The more striking point is that "theirs" was made by analogy to "his." Speakers heard "his" as the standard possessive pattern and extended it to the plural pronoun, so "theirs" follows the same logic as "his" rather than the "mine/thine" model that produced "theirn." That analogy won out in standard speech, displacing "theirn" and leaving "theirs" as the form we use today.