1To lengthen or grow longer/taller; to grow (of hair, one's height, grass, plants, etc.).
この一年で息子の背がずいぶん伸びた。
My son has grown quite a bit taller this past year.
髪が伸びてきたから、そろそろ切りに行こう。
My hair's gotten long, so I should go get it cut soon.
雨が続いて、庭の雑草がぐんぐん伸びている。
With the rain continuing, the weeds in the garden are growing fast.
ゴムは引っ張ると伸びるが、放すと元に戻る。
Rubber stretches when you pull it, but returns to shape when released.
2To straighten out, flatten, or become smooth (e.g. wrinkles smoothing out).
アイロンをかけたら、シャツのしわがきれいに伸びた。
After ironing, the wrinkles in the shirt smoothed out nicely.
丸めて保管していたポスターが、しばらく置いたら伸びた。
The poster that had been stored rolled up flattened out after being left for a while.
3To spread (of paint, cream, etc.); よく伸びる means it has good coverage and spreads easily.
このクリームはよく伸びるので、少量で十分だ。
This cream spreads well, so a small amount is enough.
絵の具に水を少し足すと、よく伸びて塗りやすい。
Adding a little water to the paint makes it spread well and easy to apply.
4To stretch out or reach out (e.g. of a hand or leg); also 手が伸びる: to find oneself reaching for something.
おいしそうなお菓子に、つい手が伸びてしまった。
I couldn't help reaching for the tasty-looking sweets.
眠っているうちに足が伸びて、毛布からはみ出していた。
While I was asleep my legs stretched out and stuck out from under the blanket.
5To lose elasticity or firmness; to go slack; (of noodles) to get soggy after sitting too long.
ラーメンは早く食べないと麺が伸びてしまう。
If you don't eat ramen quickly, the noodles get soggy.
何度も洗ったせいで、Tシャツの首回りが伸びてしまった。
From being washed so many times, the collar of the T-shirt has stretched out.
6To make progress; to develop, expand, increase, or improve (e.g. sales, grades, ability). Written 伸びる in this sense.
新商品が好評で、今期は売上が大きく伸びた。
The new product was well received, and sales grew significantly this quarter.
毎日練習を続けたら、会話力がぐんと伸びた。
After practicing every day, my conversational ability improved a lot.
あの選手は今シーズン、まだまだ伸びる余地がある。
That player still has plenty of room to grow this season.
7(Colloquial) to be knocked out, to collapse, or to be left limp from exhaustion. Written 伸びる in this sense.
強烈なパンチを食らって、相手はリングに伸びてしまった。
Taking a powerful punch, the opponent was knocked out cold on the ring.
炎天下を歩き回って、家に着くころにはすっかり伸びていた。
After walking around in the blazing sun, I was completely wiped out by the time I got home.
8To be prolonged or extended — a meeting, period, lifespan, or deadline lasting longer than planned. Written 延びる in this sense.
議論が長引いて、会議が一時間も延びた。
The discussion dragged on and the meeting ran a full hour over.
医療の進歩で平均寿命が大きく延びた。
Average life expectancy has lengthened greatly thanks to advances in medicine.
提出の締め切りが一週間延びて、少し余裕ができた。
The submission deadline was extended by a week, giving me a little breathing room.
9To be postponed, delayed, or put off to a later date. Written 延びる in this sense.
雨のため、運動会は翌週に延びた。
Because of the rain, the sports day was postponed to the following week.
部品が届かず、製品の発売が来月に延びた。
With parts not arriving, the product launch was pushed back to next month.