The name Soroptimist was coined from the Latin soror meaning sister,
and optima meaning best.
And so Soroptimist is perhaps best interpreted as ‘best for women’.

In 1921, the first Soroptimist club was formed in Alameda County, California with over 80 business and professional women from in and around the city of Oakland. With Violet Richardson as the first President, back then the first club, which changed its name to SI Oakland in 1928, met weekly, debating service projects and hearing speakers on various worldwide issues that would broaden members’ horizons.

Additional Soroptimist clubs soon followed along the Pacific and Atlantic coasts, amounting to 15 clubs in 5 years, with a growing concern for women in their communities.

A similar club was established in Britain.

In 1924 Suzanne Nöel founded Soroptimist International of Paris, the first Soroptimist club in Europe using her worldwide lecturing series to share the Soroptimist concept and messages, prompting the establishment of clubs all over Europe. Nöel later became the first President of the European Federation.

1926 was the beginning of Soroptimist in Canada, with Vancouver British Columbia being the first club chartered in this country.

1928 saw the Foundation of both the American and the European Federations and a Soroptimist International Association was created to provide a link between the Federations.

In 1934, Europe and Great Britain & Ireland were to form separate Federations. Australia joined the network in 1937 with the first club in Sydney.

In 1946 Soroptimists held a reception for delegates to UN conferences, which included Eleanor Roosevelt, and in 1948, the Soroptimist International Association was awarded Consultative status with UNESCO. In 1950, the Association was awarded category C Consultative status with ECOSOC (Economic & Social Council, United Nations). In 1952 the governing body of Soroptimist International was founded, as it is today. In 1966, UNICEF granted consultative status to Soroptimist International for service projects for children and in 1975, Soroptimists attended the First UN World Conference on Women which was held in Mexico City.

Most of this text is from
More information can be found on that website.

Since the beginning, Soroptimist International (SI) has sought to bring about change to the lives of women and girls worldwide.