inter-, intero-
(Latin: between; among, mutually, together; on the inside, internal)
Although abstracted from the many compounds in which it entered English, the form inter- was not generally considered a living prefix in English until the 1400s.
During the later period of Middle English many words borrowed in the Old and Middle French forms entre-, enter- began to be consciously respelled with Latin inter-; although vestiges of the older French borrowings are found in entertain and enterprise.
The living prefix inter- is now freely added to almost any element in English to create such formations with the meaning of "between" and "among". The words formed by intra- are closely related to this inter- prefix; in fact, they both apparently came from the same Latin source.
Motto of Columbus College, Columbus, Georgia, USA.
Motto of King Otto IV of Brunswick, Germany (1198-1215).
2: Continuing in time or space without interruption, continuous: "An uninterrupted rearrangement of electrons in the solar atoms results in the emission of light."