How do you say sparse?

"Sparse" is already the word for what you're describing, so you don't need to change it. However, depending on the context, there are other words you could use that convey a similar meaning:

Similar to "sparse" in meaning:

* Thin

* Scanty

* Scattered

* Meagre

* Sparsely populated

* Dilute

* Rare

* Fragile

* Limited

More specific alternatives:

* Undersupplied (for resources)

* Underpopulated (for areas)

* Understocked (for inventory)

* Underdeveloped (for areas or systems)

The best word to use will depend on the specific situation.