'Large' closed subgroup

Question

I am working through a paper in the field of differential geometry (Yang-Mills theory) and the author writes:

'We assume the Riemannian manifold $(M,h)$ admits a large closed subgroup $K$ of the isometry group of $(M,h)$'

Does anyone know what the terminology 'large' means?

Answer 1

Large typically means "mapping onto a non-cyclic free group", although here it may mean containing a non-cyclic free group. The latter is weaker and, by the Tits alternative in this conetxt, is equivalent to non-solvable.