It would be pedantic say that all form of pattern and repeatnis geometric – what is usually understood when the term is applied to pattern is one which is self contained and repeats at a regular recognisable interval.
In terms of furnishings the expression is to suggest that more formal pattern might be required, should be avoided, might need care, or is needed for balance…as checks, stripes, polka dot or stylised motifs as opposed to random, climbing, or all over florals.
Geometric patterns are made from any combination of mathematical form, whether a simple repeated square to the complex geometrical design which the Islamic world has perfected in Arabesque, star and tile pattern, textile, art, and sculpture.