Social change and turmoil are unpredictable: Portland has been the consistent, uninterrupted pulse of the movement.

Opportunism is changing or altering political positions for personal gain. This video explains the concept of opportunism (as well as ultra-leftism, which I think is a grossly overused term despite it having an actual use)

Defeatism, in socialist circles, is the idea that communism is impossible for whatever reason, and that we should just accept defeat and try to make the best out of capitalism. Again, pretty obvious why Marxists should oppose this one as well.

I didn't know what Tailism was, but this is what I found on it:

[Lenin] first used tailism (khvostism) to describe the ‘Economists’, those who argued that the communist party should not take the lead in a revolutionary situation, but should allow economic events – crises, strikes, unrest – to unfold on their own. The party would then pick up on the tail of these events. No way, argues Lenin; the party is the vanguard, educating, agitating, watching for opportunities.

Putschism is the idea that capitalism should be overthrown through a secret plot. Marxists object to this, as we recognize that socialism can only be achieved through a mass proletarian revolution (the exact nature of this revolution is where Marxists diverge).