Questionable

wiktionary

ref

question +‎  -able

etymonline

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questionable (adj.)

1580s, "that may be interrogated" (a sense now obsolete); c. 1600, of facts, claims, etc., "open to dispute, doubtful," from question (v.) + -able. Deprecatory sense of "dubious in character" is attested from 1806. Related: Questionably.