Where does “that've” come from?
that've (English) comes from English þat, from Middle English þat, from Old English þæt, from Proto-Germanic þat, from Proto-Indo-European tód, from Proto-Indo-European to-, from Proto-Indo-European só — this; that.
Ancestry of “that've”, step by step
that've traces back through two separate lines of ancestry.
via English þat
| Step | Language | Word | Meaning |
|---|---|---|---|
| 1 | English | þat | so, so that, in order that |
| 2 | Middle English | þat | Alternative form of that |
| 3 | Old English | þæt | nominative/accusative neuter singular of se: the;... |
| 4 | Proto-Germanic | þat | nominative/accusative singular neuter of *sa |
| 5 | Proto-Indo-European | tód | demonstrative pronoun; that; it |
| 6 | Proto-Indo-European | to- | it; that; the, that |
| 7 | Proto-Indo-European | só | this; that |
via English ’ve
| Step | Language | Word | Meaning |
|---|---|---|---|
| 1 | English | ’ve | in its sense marking the perfect or retrospective aspect |