PERTINA'CIOUS, adjective [Latin pertinax; per and teneo, to hold.] 1. Holding or adhering to any opinion, purpose or design with obstinacy; obstinate; perversely resolute or persistent; as pertinacious in opinion; a man of pertinacious confidence. 2. Resolute; firm; constant; steady. Diligence is a steady, constant, pertinacious study-- [This word often implies a censurable degree of firmness of constancy, like obstinacy.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI