Usage of "indisposed"

Quite simply:

Work makes me sick.

This has become such a prevalent excuse for missing work that it has come to be understood as not available. The book of Stobo Church, published in 1907, reveals how easily the word can be misinterpreted even in a context where its real definition is quite clear:

1770: Five times this year he was indisposed; and on four Sundays he preached elsewhere; nine in all marked no sermon. The Sacramental Fast was held.

The vicar called in sick, and the records show that, but a person who doesn't know the definition could easily misconstrue that he was "unavailable".

In Doors to Madame Marie, likewise:

You knew when a girl had her period because, as the French put it, she was "indisposed." It was a privilege to be indisposed; you could be excused from anything stressful. I kept dreaming of the day when I, too, could say that I was indisposed.

English permits pretense just as well as any language, and if we pretend long enough it becomes real to us. I rarely hear the expression used to mean "I'm sick," so my default interpretation is "I'm not available," unless the larger context indicates, "I'm sick."

Interestingly the etymology of indisposed would be quite friendly to unavailable:

c.1400, "unprepared;" early 15c., "not in order,"

from in- (1) "not" + disposed;

or else from Late Latin indispositus "without order, confused."

Mid-15c. as "diseased;" modern sense of "not very well" is from 1590s. A verb indispose is attested from 1650s but is perhaps a back-formation of this.

dispose

late 14c., from Old French disposer (13c.) "arrange, order, control, regulate" (influenced in form by poser "to place"),

from Latin disponere "put in order, arrange, distribute," from dis- "apart" (see dis-) + ponere "to put, place" (past participle positus; see position (n.)).

The conventional definition implies: parts of me are out of place. Shifting the frame of reference, the meaning becomes I myself am out of place.

The Word Detective suggests:

The emerging use of “indisposed” to mean “busy” or “unavailable” seems to be an extension of the long-standing use of “indisposed” as a euphemism employed in cases where the truth would be either embarrassing (the person is in the bathroom, for instance) or socially offensive (the person simply doesn’t wish to see or talk to you). The fact that “indisposed” is a fairly snooty-sounding word has also lent to its use as a sarcastic or humorous euphemism for being drunk, being absent from work for another reason (such as having been fired) and even for being in jail. Such humorous use of “indisposed” is fairly common in films and the more literate TV sitcoms, where the humor usually relies on “indisposed” being a substantial understatement of the seriousness of the actual situation (e.g., the “indisposed” party is dead and stuffed in the closet).

I indeed use it as a humorous euphemism for being unavailable as being in the bathroom, which makes me unavailable and not going to go into details. It is a very good word and I like having the ability in todays world to use more than one liners and a vocabulary of over five letter words. As I used to tell my children; if you don't understand a word, ASK ME or better yet look it up. I was amazed that I had a room full of High School students that I made the statement "That was pure propaganda." Not one in the class knew what the word was! I simply told one of the girls...LOOK IT UP. She didn't know how to spell it, so I did write it on the board.