Probus Clubs

Probus is a local, national, and international association of retired people who come together in non-political, non-sectarian, non-profit, autonomous clubs which provide regular opportunities for members to meet others in similar circumstances, with similar levels of interest, make new friends, and maintain and expand their interests. Probus Clubs can be made up of men, women or be mixed (men and women) clubs. It is normal for the spouses of club members and widows of former members to be encouraged to participate in the social activities.
In some places Rotary Clubs sponsor Probus Clubs but many clubs are sponsored by other Probus Clubs. By 2018, there were over 400,000 members in approximately 4,000 Probus clubs worldwide.

Above extracted from Wikipedia

Other useful links:

A Probus magazine
A probus resources website
A Probus information website