Webster's Revised Unabridged Dictionary · 1913

Interest

Interest , transitive verb

[From interess'd, past participle of the older form interess, from French intéresser, Latin interesse. See Interest, n.]

1.
To engage the attention of; to awaken interest in; to excite emotion or passion in, in behalf of a person or thing; as, the subject did not interest him; to interest one in charitable work.
To love our native country... to be interested in its concerns is natural to all men. — Dryden
A goddess who used to interest herself in marriages. — Addison
2.
To be concerned with or engaged in; to affect; to concern; to excite; -- often used impersonally. [Obsolete]
Or rather, gracious sir, Create me to this glory, since my cause Doth interest this fair quarrel. — Ford
3.
To cause or permit to share. [Obsolete]
The mystical communion of all faithful men is such as maketh every one to be interested in those precious blessings which any one of them receiveth at God's hands. — Hooker

Interest , noun

[Old French interest, French intérêt, from Latin interest it interests, is of interest, from interesse to be between, to be difference, to be importance; inter between + esse to be; compare Late Latin interesse usury. See Essence.]

1.
Excitement of feeling, whether pleasant or painful, accompanying special attention to some object; concern; a desire to learn more about a topic or engage often in an activity.
So much interest have I in thy sorrow. — Shakespeare

Interest expresses mental excitement of various kinds and degrees. It may be intellectual, or sympathetic and emotional, or merely personal; as, an interest in philosophical research; an interest in human suffering; the interest which an avaricious man takes in money getting.

2.
(Finance, Commerce) Participation in advantage, profit, and responsibility; share; portion; part; as, an interest in a brewery; he has parted with his interest in the stocks.
3.
Advantage, personal or general; good, regarded as a selfish benefit; profit; benefit.
Divisions hinder the common interest and public good. — Sir W. Temple
When interest calls of all her sneaking train. — Pope
4.
(Finance) A fee paid for the use of money; a fee paid for a loan; -- usually reckoned as a percentage; as, interest at five per cent per annum on ten thousand dollars.
They have told their money, and let out Their coin upon large interest. — Shakespeare
5.
Any excess of advantage over and above an exact equivalent for what is given or rendered.
You shall have your desires with interest. — Shakespeare
6.
The persons interested in any particular business or measure, taken collectively; as, the iron interest; the cotton interest.
Collocations (2)
Compound interest , interest, not only on the original principal, but also on unpaid interest from the time it fell due.
Simple interest , interest on the principal sum without interest on overdue interest.