A person who practices self-discipline or who is subject to discipline; one who disciplines themselves or follows strict rules.
From Latin disciplinans (disciplining), the present participle of disciplinare (to teach), with the -ant suffix indicating an agent or one who performs an action.
The '-ant' suffix names doers and agents (defendant, accountant, immigrant)—so a 'disciplinant' is literally 'one who disciplines' themselves, a rare word for highly self-controlled people!
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