1A writing or painting brush made of bundled animal hair or synthetic fibers attached to a handle, used for calligraphy, traditional painting, and handwriting practice.
書道教室で新しい筆をおろした。
I broke in a new brush at calligraphy class.
筆に墨をたっぷり含ませてから半紙に書き始めた。
I soaked the brush well with ink before starting to write on the paper.
祖父は今でも年賀状の宛名を筆で書く。
My grandfather still writes the addresses on New Year's cards with a brush.
2The act of writing or drawing with a brush, or the resulting brushwork and style — as in the expression 筆が立つ (to write skillfully).
書道展では審査員が一人一人の筆をじっくり見比べていた。
At the calligraphy exhibition, the judges carefully compared each person's brushwork.
この掛け軸は力強い筆で描かれている。
This hanging scroll is painted with bold, powerful brushwork.
3Writing as an activity, or the written text itself — as in 筆をとる (to take up one's pen) or 'a novel by his pen'.
彼女は感動を抑えきれず、思わず筆をとった。
Unable to hold back her emotion, she couldn't help but take up her pen.
この評論は鋭い筆で当時の社会を批判している。
This essay criticizes the society of that era with sharp writing.
4A counter for a single parcel of land in land registration, as in 一筆の土地 (one lot of land) — an older, specialized usage.
相続した土地は三筆に分かれていた。
The land I inherited was divided into three separate lots.
隣接する二筆の土地をまとめて売却することにした。
We decided to sell the two adjoining lots of land together.