Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ē-lūcubro, āvi, ātum, 1, v. a. (elucu-bror, deponent: epistolam, quam eram elucubratus, Cic. Att. 7, 19), to compose by lamplight, i. e. at night, with great labor, Cic. Brut. 90 fin.; Tac. Or. 9; Col. 10 praef. fin.