I lit the candle's wick.
The mechanical pencil lead broke.
Refers to the central part or inner essence of something, both physically and figuratively. Common in expressions such as 体の芯 and 芯が強い.
See also: 心 (しん)
The cold chilled me to the core.
She is a person with strong inner resolve.
pistil; stamen; flower's reproductive core
Botanical use corresponding to 蕊; depending on context, it may refer specifically to the pistil or to the stamen. In everyday speech, 花の芯 can also sound like the central part of a flower more generally.
See also: 蕊 (しべ)
In this diagram, the flower's 芯 is shown as the pistil or stamen area.
We lit the candle's wick to celebrate the birthday.
The pencil lead keeps wearing down as I write.
Walking through the snow, I got chilled to the bone.
I boiled the potatoes until they were cooked through to the center.
I removed the flower's pistil before making the arrangement.
collar core; collar stiffener