What's a sick day? What's sickness? What's a day?

I've been a bit vague on how to handle sick leave for years, since my job has the expectation of teleworking one day a week anyway and some flexibility about what day that would be. But still, in the Before Time, if I felt too ill to be too productive at work, I'd let my boss know, dress cozily, and spend the day at home relaxing. No errands outside the home if at all possible. Maybe I'd log in and work for a few hours but that would feel optional. Illness would be a valid reason to miss meetings and put off (all but the most important) deadlines. 

But now? Who the fuck knows? There's a pandemic going around which can have no symptoms for one person and kill the next person, so obviously we shouldn't leave the house if we have even the mildest sniffle. But these days we try to minimize that anyway. Is it actually a reason to skip work if work was going to be at home anyway? If I cancel all my meetings and no one was expecting any meetings with me that day, am I actually taking a sick day?

And what if I'm not actually the sick person? This post is inspired by my daughter. Today she'd be too sick to go to school in the Before Time. She's just spending all day in bed, and my schedule today isn't too busy, so I didn't take any leave. I still may regret that, though!