The term singularity is used to refer to a potential point in time when AI becomes intelligent enough to design even better AI, and hence lead to an uncontrolable spiral far exceeding human capability to comprehend or control. This may be itself regarded as a positive thing, a 'next stage of evolution', transcending humanity, or as a threat to humanity itself.
Used on Chap. 24: page 585
Links:
Encyclopedia Britanica: singularity -- technology- Wikipedia: Technological singularity