The two-photon absorption (TPA) spectrum of 4-(N,N diethylamino)-beta-nitrostyrene (DEANST) crystal has been characterized in the 760-1300 nm spectral range. It presents a broad (similar to 7000 cm(-1)) absorption band that cannot be described by any molecular resonance. In particular, it does not display the strong molecular TPA resonance that is due to the internal charge-transfer transition. Davydov splittings as large as 5400 cm(-1) are observed in the linear absorption spectrum. Thus, dipole coupling between transition dipole moments are very strong in DEANST crystal. The linear and nonlinear absorption spectra are analyzed using the framework of Frenkel-Davydov exciton theory.