late 14c., "tangible thing, something perceived or presented to the senses," from Medieval Latin objectum "thing put before" (the mind or sight), noun use of neuter of Latin obiectus "lying before, opposite" (as a noun in classical Latin, "charges, accusations"), past participle of obicere "to present, oppose, cast in the way of," from ob "in front of, towards, against" (see ob-) + iacere "to throw" (from PIE root *ye- "to throw, impel").
Sense of "thing aimed at" is late 14c. No object "not a thing regarded as important" is from 1782. As an adjective, "presented to the senses," from late 14c. Object lesson "instruction conveyed by examination of a material object" is from 1831.