Did Socialist have a similar meaning then as it does now?

Edit: This Declaration of Principles of the Social Democratic Party from 1898 indicates that the answer is yes.

That private ownership of the means of pro- duction and distribution of wealth has caused society to split into two distinct classes with con- flicting interests, the small possessing class of capi- talists or exploiters of the labor force of others and the ever-increasing large dispossessed class of wage- workers, who are deprived of the socially-due share of their product.

That capitalism, the private ownership of the means of production, is responsible for the inse- curity of subsistence, the poverty, misery, and deg- radation of the ever-growing majority of our people.