What does spirituality mean to a humanist?

Most Humanists I know - don’t care for the word at all. Precisely because it could mean anything.

However there are secular uses of the word and definitions from various groups that can help us understand what it means - outside of a religious context.

First - the Spiritual Naturalist Society - What is Spiritual Naturalism? says - “to have spirituality is to be concerned with the larger, deeper, and essential matters of life and to apply ourselves consciously toward them in a committed practice or ‘walk’. This includes, as Socrates put it, the ‘examined life’, and this is what we mean by spirituality.”

For me personally - “Spirituality, in a secular sense, is the spirit in which you approach life. In this sense, it’s critical you attend to your spiritual life because it is actually attending to your motivational needs. How you motivate yourself. Why you motivate yourself. This is the realm of philosophy. Some people attend to this need with religious philosophy. Others with secular philosophy. I attend to this need with the Humanist philosophy specifically.”

The point is - if and when a Humanist talks about spirituality - they are talking about Secular Spirituality. There is a really nice wikipedia article that explains it and the tradition of secular spirituality here - Secular spirituality - Wikipedia