Over several months, a patient has developed an increasingly persistent and pervasive difficulty finding the names of common objects and people, a difficulty that does not resolve on its own and is now affecting his ability to hold ordinary conversations. Before revealing the answer: is this lethologia?

No, this is more consistent with nominal aphasia than with lethologia. Lethologia is specifically a brief, isolated, self-resolving lapse; here, the difficulty is persistent, pervasive, and worsening over months, significantly affecting ordinary conversation, which points instead toward the broader, more significant language disturbance characteristic of nominal aphasia rather than an everyday "tip of the tongue" experience.