Hard or solid; physically firm and not easily deformed or broken (often used for metal, stone).
この金属は非常に硬いので切るのが難しい。
This metal is very hard, so it's difficult to cut.
硬い岩をハンマーで砕いた。
I broke the hard rock with a hammer.
硬い床に直接座るのは疲れる。
Sitting directly on a hard floor is tiring.
Stiff or wooden; lacking smoothness or naturalness (used for writing or speech).
初めての作文は表現が硬い。
My first essay has stiff expressions.
彼のスピーチは硬くて聴衆をつかめなかった。
His speech was too stiff to engage the audience.
この文章は言い回しが硬いので直した方がいい。
This sentence's wording is stiff, so it should be revised.
Firm or strong (not yielding or easily moved); showing firmness or solidity (e.g., a firm defense or strong support).
チームは硬い守りで相手の攻撃を抑えた。
The team held off the opponent's attacks with a solid defense.
硬い支持があればプロジェクトは進めやすい。
With strong support it's easier to move the project forward.
彼は硬い意志で研究を続けた。
He continued his research with firm determination.
Safe, steady, or reliable; trustworthy and stable (often about people or policies).
あの人は堅くて頼りになる同僚だ。
That person is a steady, reliable colleague.
彼の経営方針は硬くて無駄がない。
His management policy is solid and without waste.
硬い約束を守る人だ。
He is someone who keeps firm promises.
Obstinate or stubborn; unwilling to change one's opinion or behavior.
彼は意見が硬くて説得するのが難しい。
He is so stubborn that it's difficult to persuade him.
そんなに硬くならないで、もう少し柔軟に考えよう。
Don't be so rigid; try to be a little more flexible.
古い慣習に固執して硬くなるのはよくない。
It's not good to become rigid by clinging to old customs.
Bookish, formal, or stuffy; overly formal or stiff in wording or manner (opposite of casual).
面接で硬い話し方をしてしまい、緊張しているのが目立った。
I spoke stiffly in the interview, and my nervousness showed.
この論文は硬い文体なので一般向けには読みづらい。
This paper's stiff style makes it hard for general readers.
砕けた表現を使った方が、堅苦しさが和らぐ。
Using more casual expressions will ease the stiffness.