RATO
/ˈreɪtəʊ/(also R.A.T.O., Rato, rato) Aeronautics
noun
A system for assisting the take-off of an aircraft or missile in which a (usually detachable) unit of rocket engines is used temporarily to provide additional thrust. Frequently attributive, especially in RATO unit.
Origin
1940s; earliest use found in Joplin (Missouri) Globe. Acronym from the initial letters of rocket-assisted take- off from rocket + assisted + take-off.