Acidify (verb)

1. To make something acidic or sour.
2. To increase the acidity of a solution.

Origin:

From the latin word "acidus" meaning "sour" and the suffix "-ify" meaning to make or cause to be, the word was first used in the 18th century in english.

Examples:

1. Lemon juice can acidify water.
2. The acid rain acidified the lake.
3. He acidified the soil to make it more suitable for certain plants.
4. The vinegar was used to acidify the marinade.
5. The acidifying agent was added to lower the pH of the solution.