All 4 Uses

speculative
in
Babbitt
(Edited)

The room displayed a modest and pleasant color-scheme, after one of the best standard designs of the decorator who "did the interiors" for most of the speculative-builders' houses in Zenith.
Chpt 2 *

speculative = without certainty of payment
Yet his eventual importance to mankind was perhaps lessened by his large and complacent ignorance of all architecture save the types of houses turned out by speculative builders; all landscape gardening save the use of curving roads, grass, and six ordinary shrubs; and all the commonest axioms of economics.
Chpt 4
It was a speculative venture to call on the Rieslings; interesting and sometimes disconcerting.
Chpt 10

speculative = with much uncertainty
Babbitt was an official delegate; another was Cecil Rountree, whom Babbitt admired for his picaresque speculative building, and hated for his social position, for being present at the smartest dances on Royal Ridge.
Chpt 13

speculative = without certainty of payment

Definitions:

(1) (speculative as in: a speculative look or mind)
showing, engaged in, or having a tendency of curiosity or deep thought
(2) (speculative as in: a speculative theory)
based on thought or theory that is unproven or unprovable
(3) (speculative as in: a speculative venture)
done with uncertainty--often a risky investment for profit
(4) (meaning too rare to warrant focus)
More rarely, speculative can be used in a phrase such as speculative bubble which refers to an unsustainable increase in financial values based on market psychology. This sense of the word is based on the sense of speculative that refers to making a risky investment for profit.