Which word in the dictionary is always spelled incorrectly?

I'm usually large, and quite a bit moody. I live online, as I feel it's my duty. I run a kingdom made of threads - oh, I should probably take my meds. What am I?

You clap your hands as soon as you hear the songs that I whisper in your ear. Then I'd dance around and fly with glee as I play the violin that I always carry with me.

Tap me once, I ignore you. Tap me thrice, I still ignore you. Yet I bob back and forth, enticing you.

I’m something you cannot ever win, A battle of thought that lies within. No board, no dice, no coin is tossed... As soon as you think of it, you have already lost.