Litmus paper is used to test the acidity or alkalinity of a substance.

I used litmus paper to test the acidity of the solution.

Using litotes, he said the movie was not bad.

I bought a litre of milk from the store.

She received her Litt.D. degree from the university.

Please pick up your litter and throw it in the trash can.

He is a renowned litterateur.

Please dispose of your trash in the litterbag.

Please throw your trash in the litterbin.

Don't be a litterbug and throw your trash in the proper bin.