鞘(さや)scabbard, cap (on pen, brush, etc.), margin (between two prices), spread, markup, commission, enclosure, outer fence

先生(せんせい)：「刀(かたな)を鞘(さや)に納(おさ)めましょう。」

Teacher: "Let's put the sword back in the scabbard." {scabbard, cap (on pen, brush, etc.), margin (between two prices), spread, markup, commission, enclosure, outer fence}

鉛筆(えんぴつ)の芯(しん)を保護(ほご)するために鞘(さや)をかぶせる。

A cap is placed over the pencil lead to protect it. {scabbard, cap (on pen, brush, etc.), margin (between two prices), spread, markup, commission, enclosure, outer fence}

筆(ふで)に鞘(さや)をつけて保管(ほかん)していたら、筆(ふで)が腐(くさ)りました。

If I stored the brush with a cap on it, the brush rotted. {scabbard, cap (on pen, brush, etc.), margin (between two prices), spread, markup, commission, enclosure, outer fence}

売(う)り値(ね)と買(か)い値(ね)の差(さ)をつけるほど、鞘(さや)で儲(もう)けやすくなる。

The more you create a difference between the selling price and the buying price, the easier it becomes to profit from the spread. {scabbard, cap (on pen, brush, etc.), margin (between two prices), spread, markup, commission, enclosure, outer fence}

相手(あいて)の刀(かたな)が鞘(さや)に納(おさ)まるその瞬間(しゅんかん)までは、少(すこ)しも油断(ゆだん)できません。

You cannot let your guard down even for a moment until the opponent's sword is sheathed in the scabbard. {scabbard, cap (on pen, brush, etc.), margin (between two prices), spread, markup, commission, enclosure, outer fence}