Modicum

google

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late 15th century: from Latin, neuter of modicus ‘moderate’, from modus ‘measure’.

wiktionary

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From Late Middle English modicum, borrowed from Latin modicum(“a little, a small amount”), a noun use of the neuter form of modicus(“moderate; restrained, temperate; reasonable”) + -cum(suffix forming neuter nouns). Modicus is derived from modus(“a measure; a bound, limit”) (ultimately from Proto-Indo-European *med-(“to measure”)) + -icus(suffix meaning ‘of or pertaining to’ forming adjectives). [1]

The plural form modica is derived from Latin modica.

etymonline

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modicum (n.)

"small quantity or portion," late 15c., Scottish, from Latin modicum "a little," noun use of neuter of modicus "moderate, having a proper measure; ordinary, scanty, small, few," from modus "measure, extent, quantity; proper measure," from PIE root *med- "take appropriate measures."