Dictionary puzzle

[Mulciber]

When I'm using my Latin dictionary (it's a Collins) I sometimes come across the abbreviation fus which does not appear in the list of abbreviations at the front. I can't work out what it means. Here are a couple of examples:

chance upon vt fus incidere in, invenire.

allow for vt fus rationem habere (gen).

Any ideas?

[benissimus]

I haven't a clue. What does vt stand for? whiteoctave is quite an expert with dictionaries, perhaps he will have some input if he sees this.

[whiteoctave]

vt fus and vt sep are two mutually exclusive subdivisions of transitive verbs that some dictionaries (most notably Collins-Robert French) are wont to create. The former stands for 'fused' or 'fusionné' and is intended to unite a multi-part verb (the two of your examples are separate verbs that when combined with a preposition in an adverbial sense form a single unit) and notify the reader that the two parts must be kept together. Thus one does not 'allow X for' or 'chance Y upon'.
I presume that your Collins may occasionally put 'vt sep' after verbs that ostensibly appear the same, e.g. 'weigh down', but the latter (or sometimes former) part can be separated (hence 'sep'): 'to weigh X down' as well as 'weigh down x'. The notion of separable prefixes is, I suppose, of more import in German, with 'sich wohlfühlen' and various reflexive verbs.

~D

[Mulciber]

Thanks for clearing that up, whiteoctave. So it wasn't very important after all.