Lewis & Short

1. ap-pingo (adp-, Baiter, K. and H.), ĕre, v. a., to paint upon something (very rare): Delphinum silvis adpingit, fluctibus aprum, * Hor. A. P. 30: colorem vetusculum, Front. Or. 1, p. 229; 2, p. 257; Laud. Neglig. 2, 371.
In Cic. in epistolary style, also of writing, to add by writing, to write: adpinge aliquid novi, Cic. Att. 2, 8, 2.