The ability to re-configure oneself or join together with other vehicles or figures to create new and more powerful vehicles and figures.

Source: Superhuman Samurai Syber-Squad, toy packaging.
In other words, "our toys are like Transformers, but with more technobabble".
In the context of SSSS, the word had absolutely nothing to do with samurai. If I didn't know where "samurization" was from or what it's supposed to mean, I'd assume it meant "what a samurai does", and thus what happens to you if you, for instance, insult a daimyo, or tell a samurai that thay are without honor.