Synonyms for Tentative:

adj.

all (adjective)
doubtful.
changing (adjective)
vacillating.
conditional (adjective)
conditional, provisional, limited, iffy, contingent, dependent.
conditional, experimental (adjective)
unsettled, test, iffy, dependent, indefinite, provisional, subject to change, unconfirmed, makeshift, provisionary, contingent, undecided, provisory, probationary, not settled, not final, on trial, trial.
experimental (adjective)
investigative, test, hit-or-miss, probative, empirical, trial, benchmarked, experimental, preliminary, probationary, unverified, unproven, analytical.
exploratory (adjective)
experimental.
indefinite, uncertain (adjective)
hesitant, irresolute, doubtful, unsure, Vacillatory, vacillating, timid, halting.
irresolute (adjective)
indecisive, uncertain, hesitant, irresolute, yellow, ambivalent, irresponsible, inconsistent, impulsive, unsure, vacillating, shifty, capricious, spineless, fickle, halfhearted, fly-by-night, unwilling, Shilly-shally, unresolved, dillydallying, weak, erratic, double-minded, infirm, undependable, shrinking, changeable, volatile, shy, Flitting, watery, insipid, undecided.
provisory (adjective)
provisory.
rough (adjective)
unperfected.
uncertain (adjective)
arguable, changeable, precarious, confused, unconvinced, controversial, insecure, ambivalent, questionable, disputable, debatable, deniable, uncertain, contestable, unsure, subject to change, vague, undecided, mysterious, moot.

n.

questioning, sceptical, inclined to think/believe/agree etc., bewildered. lost, unpolished, inhibited, unfinished, start, retiring, unsure of yourself, rough, ill at ease, preliminary, sketchy, unperfected. limited, provisory. decide, Vacillatory, vacillant, timid, halting, pendulous. provisional (noun)
makeshift, unconfirmed, open to consideration, indefinite, on trial, iffy, subject to change, not settled, not final.
tentative (noun)
conditional, unsettled, provisionary, provisional, doubtful, probationary.

Other synonyms:

inhibited, questioning, Vacillatory, iffy, provisory, bewildered, unperfected, vacillant, unfinished. sketchy, unpolished, halting. pendulous, timid. lost, preliminary. rough.

Usage examples for tentative

  1. The British Foreign Office made its usual timid and tentative representation, and received the usual snub, to the effect that the Russian Government was investigating the matter as fully as possible, but had so far only arrived at the fact that the English yacht fired first. –  by
  2. Frank took a tentative step forward. – Frank of Freedom Hill by Samuel A. Derieux
  3. The latter is by itself a remarkable achievement, and constitutes the one distinctly new development brought to completion in his later years; for the modifications in his theory of individuality are only tentative – Schopenhauer by Thomas Whittaker