my Macmillan English Dictionary shows that (a)* word "desert" (a large area of land with few plants and little water...) can be used as countable or uncountable noun. But it does not give any example of using this noun as uncountable.
Could you please give me some such examples??

thank you in advance for your help,

* how it is correct : a word or the word... I'd prefer to use " a word ". But I'm not sure.
Climate change is occuring. There is more desert in the world than ever before.

* how it is correct : a word or the word... It depends on the context, on whether you want to be specific or non-specific.

Best wishes, Clive
Hello Jacek

As far as I know, the uncountable 'desert' is used only in some idiomatic phrases like "turn/change someplace into desert" and "a vast expanse/stretch of desert".

I say "the word 'desert'" rather than "a word 'desert'" because the word 'word' is specified by 'desert'.