To drive in (a nail, stake, etc.); to hammer in.
木の板に釘を打ち込んで棚を取り付けた。
I hammered a nail into the wooden board and installed the shelf.
雪の重みで支柱が抜けないように杭を地面に打ち込んだ。
I drove stakes into the ground so the posts wouldn't be pulled out by the weight of the snow.
古い床にボルトを打ち込むには、下穴を開けたほうがいい。
To drive bolts into an old floor, it's better to drill pilot holes first.
To hit (a ball, etc.); to drive; to smash a ball strongly.
彼はいつも試合でホームランを狙ってボールを打ち込む。
He always aims for a home run and hits the ball hard in matches.
フォアハンドで相手コートに強く打ち込んだ。
I hit it hard into the opponent's court with a forehand.
To fire into; to shoot into (to send a projectile into something).
狙撃手が目標に弾を撃ち込んだ。
The sniper fired a shot into the target.
壁に向かって撃ち込む練習をした（撃ち込むと書くことも多い）。
He practiced shooting into the wall (often written as 撃ち込む).
To input (data); to enter (information) into a device or system.
名前と住所をパソコンに打ち込んでください。
Please type your name and address into the computer.
会議の議事録を後で打ち込んで送ります。
I'll type up the meeting minutes later and send them.
バーコード番号を手で打ち込む必要があった。
I needed to manually enter the barcode number.
To devote oneself to; to be absorbed in; to be enthusiastic about something.
彼女は研究に打ち込んでいるため、休みがちだ。
She's so absorbed in her research that she often takes time off.
最近はゲームに打ち込んで夜更かししている。
Lately he's been so into gaming that he stays up late.
彼はボランティア活動に打ち込んでいる。
He is devoted to volunteer work.
To practice hitting (in sports); e.g., repeated batting practice.
チームは毎朝バッティングセンターで打ち込んでいる。
The team practices batting every morning at the batting center.
コーチは選手に正しいフォームで打ち込むよう指導した。
The coach instructed the players to practice hitting with the correct form.
To hit an opponent in martial arts; to land a blow.
試合で相手の懐に打ち込んで一本を取った。
In the match he struck into his opponent's chest and scored an ippon.
剣道では面に打ち込むのが基本だ。
In kendo, striking the head (men) is a basic technique.
In the game of Go, to invade the opponent's territory; to place a stone into the opponent's formation.
その手は相手の小さな陣に打ち込む良い侵入手だ。
That move is a good invasion into the opponent's small group.
To pour (concrete, etc.) into a form; to cast/fill a mold with material.
基礎工事でコンクリートを型に打ち込む作業を行った。
During the foundation work they poured concrete into the forms.