ideatum

[ahy-dee-ey-tuh m, ee-dee-] /ˌaɪ diˈeɪ təm, ˌi di-/
noun, plural ideata
[ahy-dee-ey-tuh, ee-dee-] /ˌaɪ diˈeɪ tə, ˌi di-/ (Show IPA)
1.
(in epistemology) the object of knowledge as known by the mind.
Compare datum (def 3).
Origin
1700-10; < Neo-Latin ideātum, equivalent to Latin ide(a) idea + -ātum, neuter of -ātus -ate1
British Dictionary definitions for ideatum

ideatum

/ˌaɪdɪˈeɪtəm/
noun (pl) -ata (-ˈeɪtə)
1.
(philosophy) the objective reality with which human ideas are supposed to correspond
Word Origin
C18: New Latin, from Latin: idea