"It's as same watch as the one I lost." - What is wrong with the sentence?

Question

Are the following sentences grammatically correct? If not, what's wrong with them?

1. It's as same watch as the one I lost.
2. It's the same watch as I lost.

Answer 1

1. It's as same watch as the one I lost.
2. It's the same watch as I lost.

There are two reasons that sentence one is not good. The first is grammatical, the second is semantic. When we use the degree adjective as in this way, the adjective it modifies must occur before a noun phrase with an indefinite article:

• *It's as good watch as the one I lost. (ungrammatical)
• It's as good a watch as the one I lost.

However we cannot do this with the adjective same:

• *It's as same a watch as the one I lost. (nonsense)

The first as in this sentence is a degree adverb which tells us about the degree or intensity of the following adjective. However, the adjective same is not gradable. It has a definite meaning which cannot come in degrees. When we need this gradable sense of similarity, we use the word similar. However even when we use the adjective similar we need to indicate what the thing is similar to. If it is not indicated by the context we show this using a preposition phrase headed by to directly after the noun in question:

• a similar watch to that one.

Here the phrase to that one is the Complement of the adjective similar and the whole phrase is one noun phrase. In the Original Poster's as ... as construction the thing the OP wants to compare to is a noun phrase within a separate preposition phrase headed by the preposition as. This in turn is the Complement of the adverb as, so this won't work:

• It's as similar a watch as the one I lost.

Here we can only understand this sentence if we understand that both watches are similar to a completely different watch. So the sentence above could mean, for example:

• It's as similar a watch to my father's as the one I lost.

It cannot mean that it is similar to the one I lost.

The Original Poster therefore, needs to use sentence (2). However this sentence strongly implies that this watch actually is the same watch that they lost. If they just want to say that this watch and the lost watch are the same (shape, size, colour, make and so forth), they would be better off saying:

• This watch is the same as the one that I lost.