KEY: Pertinacious.
SYN: Obstinate, persistent, wilful, dogged, persevering, determined, unyielding.
ANT: Flexible, inconstant, irresolute, volatile.
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KEY: Pertinacity.
SYN: Obstinacy, tenaciousness, adherence, resoluteness.
ANT: Irresoluteness, irresolution, indecision, hesitancy, vacillation, changeableness.
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KEY: Pertinent.
SYN: Related, connected, appertaining, appropriate, fit, apposite, just, proper, congruous, applicable.