Esperanto was created as an international auxiliary language to facilitate communication between speakers of different native tongues.

Before departure, the crew started the auxiliary power unit to power the cabin lights and avionics.

Linguists debated the merits and challenges of international auxiliary languages in the modern era.

The airline scheduled inspections of the auxiliary power units to ensure they function reliably during long-haul flights.

The ladies' auxiliaries organized a charity bazaar to support the local shelter.

Linguistics students often study modal auxiliaries when learning about tense and modality.

The International Auxiliary Language Association, founded in 1924 to study the establishment of an international auxiliary language, presented Interlingua to the public in 1951 by publishing the Interlingua–English Dictionary and the Interlingua Grammar.