thatvsthyWhat's the difference?

Quick tell: that is a conjunction, thy is a determiner, so they fill different roles in a sentence.

Which to use

“that” is a conjunction and “thy” is a determiner - they look or sound alike but fill different roles in a sentence.

#10
“that” frequency rank
#6,014
“thy” frequency rank
6024
confusion score

Side-by-Side Comparison

Feature that thy
Definition Introducing a clause that is the object of a verb, especially a reporting verb or verb expressing belief, knowledge, perception, etc. Possessive form of thou: that which belongs to thee; which belongs to you (singular).

Where the eye mixes that and thy

Muted = shared; highlighted = the visual trap. They share 2 letters in sequence.

4 ch
that
3 ch
thy

Spelling & Dictionary Insight

These two trip readers on the page rather than in the ear: that is /ðət/ while thy is /ðaɪ/. Spoken aloud the problem disappears. In writing it persists, because they differ by 1 letter(s) in length, and the parts of speech differ too (conjunction vs determiner), which is usually the fastest check. Our composite confusion score for this pair is 6024, derived from the frequency rank of both members and their visual similarity.

that is recorded at frequency rank #10, classified as aconj, pronounced /ðət/. thy is at rank #6,014, tagged as adet, pronounced /ðaɪ/.

Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.

With a confusion score of 6024, this pair ranks #513,076 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of that vs thy

Shared letters: ht. Private to "that": a. Private to "thy": y.

"that" · 4 letters · shape CCVC  ·  "thy" · 3 letters · shape CCV

Known mistypes of this pair

  • thathtat · taht · thatt · thhat · thta · tthat

Frequently Asked Questions

Can "that" and "thy" be used interchangeably?
No - they are not even the same part of speech. "that" is a conjunction and "thy" a determiner, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "that" or "thy"?
"that" is the more common of the two: it sits at frequency rank #10 in our English list, against #6,014 for "thy". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list