A Hatch

1. The act of hatching.
2. (figuratively) Development; disclosure; discovery.
3. (poultry) A group of birds that emerged from eggs at a specified time.
4. (often as mayfly hatch) The phenomenon, lasting 1–2 days, of large clouds of mayflies appearing in one location to mate, having reached maturity.
5. (informal) A birth, the birth records (in the newspaper) — compare the phrase "hatched, matched, and dispatched."