Starting from the analysis of the verbal entries in the letter A of An Anglo-Saxon Dictionary (Bosworth and Toller 1973), this paper establishes the descriptive bases necessary for the elaboration of a lexical database of Old English. The basic terms (morphological process, derivational chain, inflexion, compounding, derivation, paradigm and root) are defined, the units (affixal and non-affixal predicates, primitive predicates and derived predicates) are classified and a methodology for the identification of the affixal predicates based on distribution and decomposition is put forward. Conclusions are drawn about the nature of derivational chains, the direction of derivation, and the distinction between inflexion and derivation, on the one hand, and compounding and derivation on the other.