'Hassamayim' is not technically a real word. That is to say, it does not follow the standard pronunciations or spellings, and can only be derived by ignoring regular grammatical and etymological structure. It is included here only as a reference to correct misguided searches.

'Hassamayim' is a mistranslation of semim that has become prevalent among Hebrew scholars. Typically it is incorrectly understood to mean “the heavens”.

Some scholars will point out that hassamayim contains within it the word mayim which means “water”. This is usually the basis for some kind of weak correlation between water and the sky.

Since we now have at our disposal a consistent transliterative alphabet, we can see that although it is true that the word מימ mim is indeed contained within השמימ, it is by no means the root word. The ימ im suffix is quite evident, leaving השמ 'hasem' or שמ sem as possible roots. But since 'hasem' is just sem with the very common 'ha' prefix¹⁾, the only possible root word in 'hassamayim' is sem and the presence of the suffix clearly indicates that the word commonly pronounced hassamayim is literally none other than Legendary Ones, the Semim.