Hello,
I already found twice the word arbustum with a non standard meaning (and I found this word only with this meaning for now).
The standard meaning is “a place where trees are planted”, but the meaning I found is “bush/shrub”
Here, it’s obvious that arbustum is a single plant.
And here, arbusta is compared to arborēs.
And yet, I searched in various dictionaries, and didn’t find much. Only in the Noël dictionary, where it can translate as “tree”; otherwise, it’s “trees” or other collective/plural.
In French, the word “arbuste” (and the English “arbust”) does have this bush/shrub meaning. The correct Classical Latin word for this meaning appears to be “arbuscula”.
It looks like this word was used with some low latinity meaning and therefore can hardly be regarded as “correct”.
(Same with “silvāticus” in the meaning of “wild”, instead of “ferus”, and silvāticus is the low latinity word that has descendants with this meaning in Romance languages. But it’s another matter.)
Does someone have further information about this?