In Mexican Spanish we have the following:
• feather =
pluma
• pen =
pluma / bolígrafo - The latter does not seem to be as widespread as the former here, especially in the spoken language. I believe in some South American countries they call this a
birome.
• plume =
pluma (a single large feather) / penacho (a group of feathers)
• quill =
pluma - My Oxford Spanish dictionary gives the additional translations for this one:
pluma de ganso / pluma de oca. I have yet to hear either of them employed here to refer to the writing instrument, though. We do use
pluma de ganso, but that's when talking about the stuffing of some pillows that are supposedly filled with goose feathers.
Then there is also the archaic term
péñola , which comes from Latin
pennula (= "little feather").
Other related terms we have in Spanish (not an exhaustive list, of course) :
•
plumaje - This one can be used to refer either to all the feathers covering a bird's body or to a decorative group of feathers mounted on a helmet or a hat.
•
plumín (= nib) - Here in Mexico I've also heard this one used to refer to a felt-tip pen, especially a (very) thin one.
•
plumón - This one refers to the particularly thin feathers underneath a bird's plumage; in this meaning, it can also be written
plumión. It can be used to talk about a mattress stuffed with this kind of feathers, as well, but in Mexico I believe I've only ever heard it used meaning "felt-tip pen".
•
plumilla - I've never heard this one here, but the RAE dictionary states it's a writing instrument similar to a quill, but instead of a bird's feather it consists of a long piece of metal with a handle made of wood, bone or other materials.
•
plumier - From French and with the same meaning (= a case designed to keep pens, pencils, etc, in it).
•
plumero - A feather duster (the only meaning here in Mexico, as far as I know) or a plume (= set of decorative feathers on a hat or helmet).
•
plumería -A set of feathers or an abundance of feathers.
•
plumerío - A set of feathers.
bat (the creature)
Cat. 'a feathered rat'
Fra. 'a bald mouse'
Curious, eh?
And in Spanish, Galician and Portuguese we have "blind mice".
What distinguishes "pennenvruchten" from any other fruit? I have never heard of pen fruits.
Those fruits have nothing to do with botany.

It's a Dutch word used to refer to someone's writings, the "results (= fruits) of their pen" , their "pen produce".
