Crassesco, crassescis, crassescere. Colum. To ware bigge, thicke, fatte, or full of slethe.Nec aliunde magis, qum purgamentis eius suis crassescunt. Plin. Ware fatte.Nec crassescat in nubes. Plin. That it thicken not into a clowde.
Lewis and Short: Latin dictionary
crassesco, ĕre, v. inch., to grow thick, to thicken, grow dense or hard, grow large or fat (post-Aug.; most freq. in Pliny the elder): turtures milio, etc., Col. 8, 9, 2: sues, Plin. 13, 18, 32, 110: ceparum capita, id. 19, 6, 32, 103: pili quadrupedibus senectute, id. 11, 39, 94, 231: mel (opp. dilutum), id. 11, 13, 13, 32; cf.: vinum vetustate, id. 23, 1, 22, 40: aër in nubes, id. 2, 43, 44, 114: crassescente limo, id. 33, 5, 26, 86.