一筋

also 一条 · ひと筋 · 一すじ · ひと条

1. noun one line; one stretch (e.g. of road); one strand (e.g. of hair); one beam (e.g. of light); one ray; one length (e.g. of rope)
2. na-adjective, suffix earnest; resolute; intent; devoted; single-minded
3. noun, archaic one bloodline; one clan
4. na-adjective, archaic ordinary; common