What term is used to describe administration of substances other than by mouth?

The term "parenteral" refers specifically to the administration of substances in a manner other than through the digestive tract, which includes routes like intravenous, intramuscular, or subcutaneous injections. This method allows for direct entry of medications or nutrients into the body, bypassing the gastrointestinal system, which can be particularly beneficial when a rapid effect is desired, or when patients are unable to ingest substances orally.

In contrast, oral administration denotes substances taken by mouth and absorbed through the digestive system, while "topical" refers to applications directly to the skin or mucous membranes. The term "enteral" pertains to the delivery of substances via the gastrointestinal tract, primarily through oral ingestion or feeding tubes. Thus, parenteral administration stands out as the correct choice for describing any route that avoids the gastrointestinal tract.