Can 'ex' in 'excurare' signify 'out'?

Question

Etymonline states 'ex-' to signify 'out'

Scour: "cleanse by hard rubbing," c. 1200, from Middle Dutch scuren, schuren "to polish, to clean," and from Old French escurer, both from Late Latin excurare "clean off," literally "take good care of," from Latin ex "out" (see ex-) + curare "care for, take care of" (see cure (v.)). [...]

but Wiktionary states it to signify 'throughly':

Scour: Probably from Old French escurer, from Medieval Latin scūrō, escūrō, excūrō (“I clean off”), from Latin ex (“thoroughly”) + cūrō (“I take care of”).

1. I understand the rightness of 'thoroughly', but not 'out'. In English, we can say

to take care of someone/something thoroughly,

but not

to take care of something out.

Even if Etymonline's wrong, is there any possibility for 'out' (Germanic, and not Latinate) to fit here? Which exactly does 'out' signify?

Answer 1

As Draconis says, some praefixes can be used to express an extra nuance to a verb. Ex- and per-, for example, can express an added sense of completion, thoroughness, or intensity.

It's not so extremely surprising that ex- "out" should lead to "completion", though. Cf. English outlast, outlive: when you perform a certain activity long enough, you emerge out of the group of average people. Something that sticks out is or leads to the end of some object, so "out" and "end" may be felt to be semantically related, if vaguely. Cf. also existo "to stand out(side), to be in the outside world, to be in reality, to exist".

Per and English through both signify some sort of movement through an opening or surrounding circumstance. When you go through something, you come out at the end, so you're finished with it. So it makes some sense for both words to also indicate thoroughness or completion, cf. perterreo "to frighten through and through". Note also that English through and thorough are cognates.

Of course the semantic developments above are somewhat arbitrary: they could have gone in various different ways. I'm just showing how it probably happened in these cases.

Answer 2

You're right that ex is a preposition meaning "out from". But when used as prefixes, a great many Latin prepositions are just intensifiers, without any remnant of their original meaning. This is much more common in Later Latin but also happens in Classical times.

This seems to be one of those cases. Ex here intensifies the verb but doesn't have any sense of "out of". The verb was created in Mediaeval times, when prefixes were much more likely to lose their original meaning like this.