Etymology. From ants + -y, as in ants in one's pants. First noted as a rural Southern USA figure of speech in the early 20th century.
Is Antsy a British word?
I only discovered that antsy was American when the Association of British Scrabble Players moved to a combined British-American dictionary (soon to be replaced by another one). Antsy is an important word to Scrabblers because of its comparative form: antsier.
What is antsy short for?
Antsy came first, in the 1830s, but the idea is similar to the 20th century expression "have ants in your pants." Imagine how you'd squirm if you actually did feel ants crawling around in your pants: figuratively, that's how it feels to be antsy.
Does Antsy come from ants in your pants?
If someone is antsy, they are nervous or impatient.