filter, philtre

Filter or filter means a substance or device used to remove particles from liquid or air--
You forgot to put a filter in the coffee maker; the coffee's full of grounds.
The heater needs a new filter; this one's full of dust.

Filter may also mean a screen used to soften light, as in photography--
You can use a fine piece of cloth over the lens as a filter.
The photographer used a filter to make the scene look misty and romantic.

Philtre or philtre ( sometimes spelled philter, rhymes with filter ) means a magic potion or drug--
The philtre will put him to sleep, but when he wakes up he'll be in love with the first person he sees.
They visited an alchemist, in quest of a philtre that could help them.

Philtre may also mean the groove on the top of the upper lip--
That old photo isn't him; the philtre is much less pronounced.

Now that you know that, you can say--
"The old sorceress used a bird's nest to filter the bones out of the love philter she was concocting."