Emily Dickinson Lexicon

AS-CER-TAIN, v.t. [from the L. ad certum, to a certainty.]

1. To make certain; to define or reduce to precision, by removing obscurity or ambiguity. The divine law ascertains the truth. – Hooker.
2. To make certain, by trial, examination or experiment, so as to know what was before unknown; as, to ascertain the weight of a commodity, or the purity of a metal.
3. To make sure by previous measures. The ministry, in order to ascertain a majority in the House of Lords, persuaded the Queen to create twelve new peers. – Smollett.
4. To make certain or confident, followed by pronoun; as, to ascertain us of the goodness of our work. [Unusual.] – Dryden.
5. To fix; to establish with certainty; to render invariable, and not subject to will. The mildness and precision of their laws ascertained the rule and measure of taxation. – Gibbon.