‘Laid’ and ‘layed’ can be frequently confused, especially for people who are new to the language, because one of them looks much more natural to use than the other. However, the difference is that while they once meant the same thing, one is no longer used as a word.
‘Laid’ is the past tense and past participle of the word ‘lay’. ‘Lay’ most often means to set something down, both figuratively and metaphorically. It can mean to put something down on a surface.
“He laid the book on the table.”
It can mean to create or prepare something.
“The architects laid out the blueprints for the building.”
This is especially common in the phrase ‘lay an egg’, which means to produce one. They word has also become associated with bets.
“She laid a bet on the first horse entered into the race.”
“I’ll lay odds that you don’t know how to swim.”
In this case, ‘lay odds’ is a slang term for making a bet.
‘Layed’ is a more complicated story. It is no longer a proper word. It is considered archaic. That is, it might still be used when someone is trying to create an old time feel, but nobody uses it outside of that.
Most of the time in English, verbs can be changed from present tense to past tense by adding an –ed to the end. For example, ‘walk’ becomes ‘walked’.
However, this is sometimes not the case when the verb ends in Y. Regular verbs are ones that have a regular conjugation: the past tense and past participle end in –ed.
Either the –ed is added to the end, like ‘talk’ to ‘talked’, or just the –d is added when the verb already ends in an E, like ‘smoke’ to ‘smoked’. Then there are the irregular verbs, which do not follow that pattern.
Some verbs that end in Y are not regular. The ones that have a consonant before the Y are almost always regular. For many of them, when you turn it into past tense, you turn the Y into an I and then add –ed to the end. For instance, ‘try’ becomes ‘tried’.
There are a few exceptions, such as ‘enjoy’ and ‘enjoyed’, as well as ‘stay’ and ‘stayed’. Those past tense forms are pronounced differently from other verbs ending in Y: ‘tried’ has a long I sound in it, while ‘stayed’ does not.
However, when the letter before that is a vowel, like in ‘say’, then there is no E added. ‘Say’ just becomes ‘said’, ‘pay’ becomes ‘paid’, and ‘lay’ becomes ‘laid’.
That spelling rule was not always the case in English, as evidenced by the fact that ‘layed’ once was accepted. The reason it was changed was because of the pronunciation. In modern English, the –ed at the end of verbs is pronounced with just the D sound.
Long ago, the –ed was pronounced with the ‘eh’ sound as well as the D sound. It is likely that some verbs with a vowel sound before the Y were the first to be pronounced in a way closer to modern English.
In some older texts, such as The Faerie Queene from 1590 (over 400 years ago), the spelling was ‘layd’, which would seem to indicate a more modern pronunciation.
If it was the case, then the spelling ‘layed’ would not have reflected the pronunciation, so they may have changed it before the spellings were completely set in stone.
To summarize, the word ‘laid’ is the past tense of ‘lay’. ‘Layed was once the most common spelling of ‘laid’, but it has fallen out of use. Now, only ‘laid’ is used.