If you abstain, you're consciously, and usually with effort, choosing to hold back from doing something that you would like to do. One may abstain from a vice, for example, or in parliamentary procedure, one might abstain from placing a vote. So it's no surprise that abstain traces back through Middle English and Anglo-French to the Latin abstinēre, which combines the prefix ab- ("from, away, off") with tenēre, a Latin verb meaning "to hold." Tenēre has many offspring in English—other descendants include contain, detain, maintain, obtain, pertain, retain, and sustain, as well as some words that don't end in -tain, such as tenacious. Abstain, like many of its cousins, has been used by English speakers since at least the 14th century.