A brush (bundle of bristles or hairs) used for calligraphy, painting, etc.; can also refer historically to a pen.
書道用の筆を買いに専門店へ行った。
I went to a specialty shop to buy a calligraphy brush.
画家は細い筆で背景を描いた。
The painter painted the background with a thin brush.
この筆は毛が柔らかくて扱いやすい。
This brush has soft bristles and is easy to handle.
Brushwork; writing or drawing with a brush; the penmanship or brush style of a piece.
明日の展示には筆で描いた作品も出ます。
Some works painted with a brush will be in tomorrow's exhibition.
彼の筆は力強さがあって印象的だ。
His brushwork is powerful and impressive.
年賀状は今年は毛筆で書いてみた。
This year I tried writing New Year's cards with a brush.
Writing/composition; the written word (often referring to an author's writing).
彼女の筆はいつも優雅だ。
Her writing is always elegant.
新聞で彼の筆による記事を読んだ。
I read an article written by him in the newspaper.
作家は筆を休めず作品を書き続けた。
The writer kept writing without putting down the pen.
A counter/term for a plot of land (one parcel); an older/less common usage referring to a land lot.
その土地は一筆で売買された。
That land was bought and sold as a single parcel.
登記簿には一筆ごとに面積が記載されている。
The registry lists the area for each lot (each parcel).