The hardnesses of the minerals varied widely across the sample, affecting how easily they could be scratched.

In usage notes, editors mention hard on as an alternative form to hard-on.

Hard introduced himself at the community center and volunteered to help with the project.

The old inn stood hard by the river, its windows glowing with lamplight.

I saw the team hard at it, finalizing the project before the deadline.

The die-hards refused to accept the ticket price increase and organized a protest outside the stadium.

At the trivia night, the try-hards arrived early with notebooks and flashcards.

The meeting was dominated by blow-hards who spoke loudly but said nothing of substance.

Please bring a hard copy of your presentation to the meeting in case the projector fails.

My grandmother, who is hard of hearing, prefers written notes during visits.