I'm using the term coloquially. I admit, I'm only discovering that I was now.
Generally, I think people use it to mean a government taxing and spending, don't they?
If by people, you mean right wing pundits trying to demonize social democracy and mainstream economics in order to support for their own pseudo-scientific version then sure.
What term should I be using?
It depends on the context, but some of if falls under social democracy while other parts fall under economics/market theory. Spending for reasons fairness, equability, justice or compassion generally fall under the social democracy heading. Economics is a little more complicated to explain
There is a tendency in the US to paint business and market economies as two sides of the same coin, but this isn’t really the case. (Economists typically support the Democrats by ~ 3:1 margin) The reality of modern economics is that you can often get better overall economic performance by addressing market failures either though regulation or by having government provide the service directly. The caveat is that you need to look at each policy on a case by case basis because there is always the risk of government failures that take an even bigger toll on economic efficiency than market failures.
Business, however, loves market failures because that’s where the greatest profits are. Perfectly completive markets actually converge on profits that are near zero because competitors undercut each other until there is no profit left or force them to spend on R&D to leapfrog each other to produce better and better products.
Socialism tends not to create efficient markets because its prone to government failures. By labeling ALL government actions to make markets more competitive and/or efficient as Socialism business related special interest can limit government actions to address real issues with market efficiency which in turn means they can exploit these inefficiencies for their own profit even though it’s harmful to the overall economy.
In terms of economics, therefor the political spectrum looks something like this:
Left: Characterized by heavy government intervention in the economy, Government failures tend to limit economic growth and prosperity. There is no such party in the US, but if there was a Socialist party this is where it would sit.
Center: Characterized by selective government intervention based on balancing the risk between government and market failure. In balancing the risk of government vs market failures Center Left would favor risking government failure, center right (Eg Mainstream Democrats) would favor risking market failures.
Right: Characterized by rejecting nearly all government actions to improve market efficiency even when it’s clear that market failures are an issue. Just as with government failures on the Left, market failures limit growth and prosperity.