I occasionally see this in writing.

Problem:
“Miniscule” is meaningless.

Explanation:
People use “miniscule” as if it were an adjective that means small or tiny. Unfortunately, this is a misspelling of “minuscule” (notice the “u”), which means lowercase or (of letters) small.

In other words, “minuscule” is a typesetting word. Its complementary typesetting word is “majuscule”, which means uppercase or (of letters) capital.

I believe that those who use “miniscule” are not hearing “minuscule” pronounced correctly (or they’re mis-hearing the pronunciation) and they believe that it sounds more intelligent than “small” or “tiny”. Well, it doesn’t sound more intelligent to those who know what the proper word is and what that word means. They should stick with “small” or “tiny” and leave “minuscule” to typesetters.

Solution:
Never use “miniscule”. Use “minuscule” when referring to lowercase letters; use an adjective such as “small” or “tiny” when referring to size.