Seems to me many, many Americans confuse socialism with communism, but there definitely seems to be a negative connotation to the word socialism as used in common American parlance. Socialism, as a word or concept, is so broad, that it can be almost anything where a government intervenes to provide a backstop to less advantaged members of society. In it's broadest sense I would consider socialism as a way to mitigate some of the more destructive aspects of pure and unadulterated capitalism.
My favorite definition of socialists is "Socialists generally argue that capitalism concentrates power and wealth within a small segment of society that controls the means of production and derives its wealth through a system of exploitation. This creates a stratified society based on unequal social relations that fails to provide equal opportunities for every individual to maximise their potential, and does not utilise available technology and resources to their maximum potential in the interests of the public"
This, to me, is not an argument against capitalism, though some self-defined socialists think capitalism itself is 'evil', I see it more as a way of preventing greedy people who have the means of exploiting other with lesser means of creating an unstable and inhumane society where many people are hard against the wall and a few people are ridiculously well off due to their ability to amass great wealth at the expense of others labour and resources.
However, America has a history which favours capitalism, due to its origins as a country vastly rich in land and natural resources, and pretty short on labour force. This is no longer the situation in America, so maybe its time to rethink how its society is structured??? Oh wait, America is already very much socialised in many aspects of it structure. So maybe those that oppose the idea should just modernise their views and accept that "by the people, for the people" means all people, not just those with the means to influence the current political inbalance...?