Although metre is often considered a synonym for time signature, e.g. 4/4 or 6/8, its real meaning is more subtle. Metre could be defined as the hierarchical organization of bars, of beats and of subdivisions of beats in such a way that, with respect to time, a regular pattern appears that can be recognized as a time signature.
Select Bibliography
Butt, John. Bach Interpretation — Articulation Marks in Primary Sources of J. S. Bach (Cambridge: Cambridge University Press, 1990).
Demeyere, Ewald. Johann Sebastian Bach’s Art of Fugue — Performance Practice Based on German Eighteenth-Century Theory (Leuven: Leuven University Press, 2013).
Houle, George. Meter in Music, 1600-1800: Performance, Perception, and Notation (Bloomington: Indiana University Press, 1987).
Lohmann, Ludger. Die Artikulation auf den Tasteninstrumenten des 16.-18. Jahrhunderts (Regensburg: Gustav Bosse Verlag, 1990).