Wiktionary
n. Any of several red or yellow North American ants, of the genus ''Solenopsis'', that can inflict a harsh sting.
WordNet
n. omnivorous ant of tropical and subtropical America that can inflict a painful sting
Wikipedia
Fire ant is the common name for several species of ants in the genus Solenopsis. They are, however, only a minority in the genus, which includes over 200 species of Solenopsis worldwide. Solenopsis are stinging ants and most of their common names reflect this, for example, ginger ants and tropical fire ants. Many species also are called red ants because of their light brown color, though species of ants in many other genera are similarly named for similar reasons. Examples include Myrmica rubra and Pogonomyrmex barbatus.
None of these names applies in all countries nor to all species of Solenopsis, nor only to Solenopsis species; for example the colloquial names for several species of weaver ants in the genus Oecophylla in Southeast Asia include "fire ants" because of their red color and painful sting; the two genera, however, are not closely related. Also, Wasmannia auropunctata is commonly called the "little fire ant".
Usage examples of "fire ant".
Quietly burping a vapor of molten lava and dragon snot, a venom of fire ant, an essence that certain Middle Eastern governments might surely have converted to weaponry, she got hold of her emotions.
If ever you wish to know what the bite of a jungle fire ant feels like, reverend friars, hold one of Master Xibalba's crystals between the sun and your bare skin.
No more than I'd mind being staked out naked on a fire ant nest, Anna thought, but said nothing.
And don't be fooled by the big sign -- there ain't no seven hills, unless they're advertising their godawful fire ant mounds.