What's really neat linguistically is that "helicopter" isn't a compound of "heli" and "copter," but rather "helico" (as in helix, helical) and "pter" (as in pterodactyl).
"Rebracketing" is when this happens (i.e., the split in the word is moved in colloquial language).
I think an issue here is that taxonomic and colloquial definitions don't always agree.
Spiders are colloquially bugs, but they're not taxonomically "true bugs" (which is itself a colloquialism for Hemiptera). Tomatos are colloquially vegetables but taxonomically fruits...but afaik vegetable is a purely colloquial term anyway.
And as someone else in the thread mentioned, colloquial berries are not always taxonomic berries.
So...colloquially, "plants" sorta means, "macroscopic multicellular living non-animal thing," but taxonomically it's something else.