RhymeZone: ach definitions

Definitions of ach:

noun: (obsolete) Any of several species of plants, such as smallage, wild celery, parsley.
noun: (banking, US) Initialism of Automated Clearing House., an electronic banking network often used for direct deposit and electronic bill payment.
noun: (military, US) Initialism of Advanced Combat Helmet.

(Definitions from Wiktionary)