Hyphenate, Aspirate

For the longest time I thought that lowercase was spelled with a hyphen, but it’s actually spelled without one. And the preferred spelling is without a space between lower and case at all.
My mind reels. How long have I been doing this? When did I think that a hyphen was needed? Why didn’t spellcheck and autocorrect fix it all these years?
I open my custom dictionary, add the entry, and click Save.
What else have I misspelled all these years like some country bumpkin?
I shut down the laptop and write down a reminder on my notepad. In upper-case.