to make (a thing) one's business

Webster's Dictionary (GCIDE)

1.That which busies one, or that which engages the time, attention, or labor of any one, as his principal concern or interest, whether for a longer or shorter time; constant employment; regular occupation; as, the business of life; business before pleasure. [1913 Webster]

Wist ye not that I must be about my Father's business?— Luke ii. 49.[1913 Webster]

2.Any particular occupation or employment engaged in for livelihood or gain, as agriculture, trade, art, or a profession. "The business of instruction." --Prescott. [1913 Webster]

3.Financial dealings; buying and selling; traffic in general; mercantile transactions. [1913 Webster]

It seldom happens that men of a studious turn acquire any degree of reputation for their knowledge of business.— Bp. Popteus.[1913 Webster]

4.That which one has to do or should do; special service, duty, or mission. [1913 Webster]

The daughter of the King of France, On serious business, craving quick despatch, Importunes personal conference.— Shak.[1913 Webster]

What business has the tortoise among the clouds?— L'Estrange.[1913 Webster]

5.Affair; concern; matter; -- used in an indefinite sense, and modified by the connected words. [1913 Webster]

It was a gentle business, and becoming The action of good women.— Shak.[1913 Webster]

Bestow Your needful counsel to our business.— Shak.[1913 Webster]

6.(Drama) The position, distribution, and order of persons and properties on the stage of a theater, as determined by the stage manager in rehearsal. [1913 Webster]

7.Care; anxiety; diligence. [Obs.] --Chaucer. [1913 Webster]

To do one's business, to ruin one. [Colloq.] --Wycherley.

To make (a thing) one's business, to occupy one's self with a thing as a special charge or duty. [Colloq.]

To mean business, to be earnest. [Colloq.] [1913 Webster]

Syn: Affairs; concern; transaction; matter; engagement; employment; calling; occupation; trade; profession; vocation; office; duty. [1913 Webster]