I "know" most words on both. That is to say, I know that a solenoid is a kind of switch (a common failure point in the ignitions of 1960s cars), and I know that "taffeta" is a kind of fabric. But if you sent me into an auto parts store with the labels in an script I don't know (Chinese, Arabic, etc.) my chances of coming out with a solenoid would be not much better than my chances of getting taffeta in a fabric store so labeled. Likewise "paladin" fits somewhere in a medieval warfare context, but can I define it? I think that Roland and Oliver might have been paladins.
The good news is that I can identify wisteria for several weeks every year...
Actually, a solenoid is just a coil [1], which in electronics can be used to turn a current into a magnetic field. It is used to implement switches, but has other applications as well. For example, the CMS (Compact Muon Solenoid) [2] experiment uses theirs to generate a strong magnetic field to bend the tracks high-energy charged particles.
Context matters... ask most auto buffs, or the clerk behind the counter at Advance Auto Parts, what a "solenoid" is and they'll tell you (rightly) that it's a relay that controls the high-current circuit between the battery and the starter, using the low current circuit through the ignition switch.
The good news is that I can identify wisteria for several weeks every year...