ad- ‘to’ + plicare ‘to fold’

source: [ネトゲの嫁は女の子じゃないと思った？の瀬川茜が玉置亜子にサンオイルを塗るGIF画像｜無料GIF画像検索 GIFMAGAZINE 946540]

verb (applies, applying, applied)

1. no object make a formal application or request:

〖apply (to A) (for B/to do)〗 〈人が〉(A〈人･組織など〉に)(B〈職･入学･許可など〉を, …するために)(正式に書類などで)申し込む, 志願, 出願する; 依頼する, 問い合わせる

e.g. you need to apply to the local authorities for a grant

e.g. with infinitive : a number of people have applied to vote by proxy.

put oneself forward formally as a candidate for a job:

e.g. she had applied for a number of positions.

2. no object be applicable or relevant:

〖apply (to A)〗 〈規則･意見などが〉(A〈人･状況など〉に)当てはまる, 適用される (!進行形にしない)

e.g. normal rules apply

e.g. the offer does not apply to unionized workers.

with object bring or put into operation or practical use:

〖apply A(to B)〗 〈人が〉A〈規則･方法など〉を(B〈個別の状況･活動など〉に)適用する, 当てはめる, 応用, 利用する (!しばしばcan, willなどと共に受け身で; → 分詞applied)

e.g. the oil industry has failed to apply appropriate standards of care.

3. with object put or spread (something) on a surface:

【表面に】〈塗料･のりなど〉を塗る; 〈薬･化粧品など〉をつける «to, over» (!put A onと違い, 説明書きなどでよく用いられる)

e.g. the sealer can be applied to new wood.

administer:

«…に» 〈力など〉を加える, かける «to, on» ; ｟かたく｠ 〈人･車が〉〈ブレーキ〉をかける

e.g. smooth over with a cloth, applying even pressure.

4. (apply oneself) give one's full attention to a task; work hard.

〈人が〉 «…(すること)に» 〈心など〉を向ける; ; 〖～ oneself〗 一生懸命やる, «…に» 熱中専念する «to (doing)»

late Middle English: from Old French aplier, from Latin applicare ‘fold, fasten to’, from ad- ‘to’ + plicare ‘to fold’.