Both Uses of

lapse

in

The Great Gatsby

Gatsby took an arm of each of us and moved forward into the restaurant, whereupon Mr. Wolfshiem swallowed a new sentence he was starting and lapsed into a somnambulatory abstraction.
p. 69.9 *

lapsed = changed behavior or state

The straw seats of the car hovered on the edge of combustion; the woman next to me perspired delicately for a while into her white shirtwaist, and then, as her newspaper dampened under her fingers, lapsed despairingly into deep heat with a desolate cry.
p. 115.0

Definitions:

(1) (lapse as in: a lapse in judgement)
a change in behavior or state--usually undesired such as a temporary failure
The exact meaning of this sense of lapse is often subject to its context:
- basic example that simply indicates an undesired change in behavior -- "lapsed into alcoholism"
- example indicating that the change was short-term and due to a failure (often of effort or diligence) -- "a lapse in judgment"
- example indicating return to a previous undesired behavior or state -- "lapsed into her old bad habits"
- examples indicating a change in what was occurring where the change is not necessarily negative -- "There was a lapse in the conversation," or "She stopped talking as she lapsed into her own internal world."
(2) (lapse as in: allowed the policy to lapse)
end or terminate -- often of legal rights or of a person's association with an organization
(3) (lapse as in: after the lapse of many hours)
a period of time -- often a period that has passed