Definition of infra:
We think of the Gutenberg Bible, the Nuremberg Chronicle, the mighty editions of the Fathers, the polyglot Bibles of Paris, London, and Antwerp,- fairly to be called limp teachers' Bibles,- the 1611 Bible, the Shakespeare folios; then of the quarto editions of Addison, Pope, Walpole, and their contemporaries, and the stately octavo editions of the same writers; and finally of the myriad infra that have swarmed from the press during the last century.- "The Booklover and His Books", Harry Lyman Koopman.
And thus possibly the conditions then obtaining involved a progressively increasing complexity of material structure the genesis of the elements, from an infra- hydrogen possessing the simplest material configuration, resulting ultimately in such self- luminous nebula as we yet see in the heavens.- "The Birth-Time of the World and Other Scientific Essays", J. (John) Joly.
- "The Nature of Animal Light", E. Newton Harvey.