Why do some verbs combine the "y" and the "e" in the past tense, while others retain "ye"? For example, pay to paid, but flay to flayed?

Is there a rule for this change?

Any help would be appreciated. Thank you.


  • I don’t actually know the answer to this, but I would suspect that it could have something to do with whether the y in question derives originally from being the latter part of a simple diphthong, or from a weakened /g/. The old pret. and pp. of ‘flay’ (viz., flog and flagen) show that there is an original /g/ in there. ‘Pay’, on the other hand, entered English from French paier with just a diphthong. ‘Lay’ does not quite fit there, though, since it does have an old /g/ (it was lecgan in Old English) … But then no one ever expected English orthography to be consistent! Nov 26 '13 at 13:47
  • Pay is from Old French n. paie, v. paier "to pay, pay up" (etymonline) -- which is probably why it's paid in the p.t. However, paying and payer follow the newer y spelling. Cf. say, lay.
    – Kris
    Nov 26 '13 at 13:51
  • @JanusBahsJacquet it was once much more consistent, and therein lies the answer; it happened when the more complicated but more consistent rules of Old English degenerated into the rules of Modern English which are simpler, but have more exceptions as a legacy of those more complicated rules.
    – Jon Hanna
    Nov 26 '13 at 15:24
  • Closely related if not a dupe: Origin of different past tenses for verbs with the same endings?
    – RegDwigнt
    Nov 26 '13 at 15:25
  • 1
    Looking at the OED, in Middle English the past tense of pray and pay were spelled in many different ways, including prade, praed, praid and payde, paied, paid, payed. These spellings don't seem to me to indicate any difference in pronunciation, so I would guess it's just chance they are now spelled differently. Nov 26 '13 at 19:43

While there is a rule, I'm afraid it's not a very useful one.

It originates in the history of English which once had several well-defined classes of verbs with different reasonably predictable changes for changes in tense, number and person.

The good news is that for the most part Modern English is much simpler, with the only productive form (that is, form used with new words) being the addition of -ed, perhaps after removing a final e.

The bad news is that the old ways left a mark on the English language both in terms of some words still having preterite and past participle forms that aren't just created from adding on -ed, and which have mutated in slightly different ways to each other, making these much less regular than the Old English equivalents.

And there are also some words that are more recent (pay came into Middle English from Old French, not Old English), that have forms modelled on one of these forms (pay/paid matches say/said).

Sometimes verbs moved from one form to the other as described here.

So, the "why" is in that history, but alas the "rule" became deeply inconsistent over the course of that history, so now they just have to be learnt as irregularities. The one good thing here is that it tends only to happen to the more common verbs (a word that wasn't well-known would end up mutating to -ed through people not knowing the "correct" way), so while it's a bit of learning up front, eventually you can be fairly confident that more advanced vocabulary will almost all be of the -ed form.


I would say the rule is in the grammar. The verbs to lay, to pay and to say are contained in the list of irregular verbs, to flay is not contained in that list. By the way, it is not a vowel change, only y changes to i.

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