Allo

Allo is a term that can refer to several distinct concepts in language, science, and technology, depending on the context.

As a linguistic and scientific prefix, allo- derives from the Greek allos meaning "other" or "different." It is used to indicate deviation or distinction relative to a reference. In biology and medicine, examples include allogeneic (transplantation or tissue derived from genetically different individuals of the same species), allopolyploid (organisms with chromosome sets from different species), and allosteric (regulation occurring at a site other than the primary active site). The prefix also appears in terms such as allomorph (a morpheme variant) and allomorphy in linguistics.

Allô, with the diaeresis on the final o, is the common French telephone greeting equivalent to “hello.” It is used when answering a call and is widely recognized in francophone regions.

Google Allo was a messaging app developed by Google, announced in 2016 and released later that year. It integrated with Google Assistant to provide smart replies and conversational features within chat conversations. Google Allo was discontinued in March 2019, after which Google redirected efforts to other messaging and assistant technologies.

In sum, allo or allô cover a prefix meaning “other” in scientific terminology, a French term for answering the telephone, and a short-lived Google messaging service, each arising from different linguistic and technological paths.