1610s, from Latin unanimus "of one mind, in union," from unus "one" (from PIE root *oi-no- "one, unique") + animus "mind, spirit" (see animus). Related: Unanimously.
Entries linking to unanimous
*oi-no-
Proto-Indo-European root meaning "one, unique."
It forms all or part of: a (1) indefinite article; alone; an; Angus; anon; atone; any; eleven; inch (n.1) "linear measure, one-twelfth of a foot;" lone; lonely; non-; none; null; once; one; ounce (n.1) unit of weight; quincunx; triune; unanimous; unary; une; uni-; Uniate; unilateral; uncial; unicorn; union; unique; unison; unite; unity; universal; universe; university; zollverein.
It is the hypothetical source of/evidence for its existence is provided by: Greek oinos "ace (on dice);" Latin unus "one;" Old Persian aivam; Old Church Slavonic -inu, ino-; Lithuanian vienas; Old Irish oin; Breton un "one;" Old English an, German ein, Gothic ains "one."
animus n.
1820, "temper" (usually in a hostile sense), from Latin animus "rational soul, mind, life, mental powers, consciousness, sensibility; courage, desire," related to anima "living being, soul, mind, disposition, passion, courage, anger, spirit, feeling," from PIE root *ane- "to breathe."
It has no plural. As a term in Jungian psychology for the masculine component of a feminine personality, it dates from 1923 (compare anima). For sense development in Latin, compare Old Norse andi "breath, breathing; current of air; aspiration in speech;" also "soul, spirit, spiritual being."