Resembling or having the characteristics of a gnat; very small, tiny, or insignificant.
From gnat (a tiny flying insect) plus the suffix -like, meaning resembling or similar to; gnats being stereotypically small led to this meaning of diminutive.
Using 'gnat-like' to describe something small is brilliant because gnats are so tiny they're basically invisible—so anything gnat-like is almost impossibly small!
Complete word intelligence in one call. Free tier — 50 lookups/day.