How can I look up the words that describe various symbols?

You see symbols and things of all kinds all the time:
Division sign ÷
Degree mark °
Trademark™
Pilcrow ¶

If you don’t know what the word is for the symbol (as I didn’t for the pilcrow—I always just used to call it until now had awkwardly called it “that paragraph marker backwards-P thing”), how can you look up the word for it? For that matter, it doesn’t have to be “a symbol”, it could be almost anything. I mean, if you don’t know what a pad eye is, or a clevis pin, or a spinnaker or a crescent wrench—when you see the words you can easily google the thing or its definition / description, or ask someone, using the words. But when you see the thing itself and don’t know it, how do you look it up?