A Dictionary of Music and Musicians/In Nomine
IN NOMINE. A somewhat vague name, bestowed, by old English writers, on a certain kind of Motet, or Antiphon, composed to Latin words. It seems to have been used, in the first instance, for compositions the text of which began with the words in question, or in which those words were brought prominently forward: such as the Introit, 'In nomine Jesu'; the Psalm, 'Deus, in nomine tuo'; and other similar cases. But its signification certainly became more extended: for Butler, writing in 1636, commends 'the In nomines of Parsons, Tye, and Taverner,' just as we should commend the Madrigals of Weelkes, or Morley, or Gibbons. The name is even employed for instrumental pieces.
The term, In nomine, is also very reasonably applied to a Fugue, in which the solmisation of the answer does not correspond with that of the subject, and which, therefore, is a fugue in name only. [See Hexachord.][ W. S. R. ]