r/grammar

On some YouTube videos, including those on the @chubbyemu channel (which I mostly enjoy), the word “bacterium” is never used. When talking about a single one or a single variety, the plural form “bacteria” is used instead. I think that I’ve even heard “a bacteria” on someone’s videos.

Is “bacteria” now both the single and plural form among scientists and physicians? If so, why? Has it been agreed that “bacterium” should never be used now? When? Who decided this?

I haven’t done science in decades. Maybe this is standard.

The correct one is “lie down on your back”, right?

Like, we say it like "I have a doctor's appointment today at 2". But why do we not say "I have a dentist's appointment at 2:30" or whatever?

Same with eye doctor. We don't say, or at least, I never really hear people say "I have an eye doctor's appointment". It's usually just "eye doctor appointment" or "eye appointment". (But then again, that could possibly more or less justsimply be due to regional dialects.)

Why does the primary care doctor get the possessive S but not any other kind of doctor?