HARP ON
VERBS
1790 ► DING to reiterate, to repeat, to importune; to harp on one subject → Sc. & Eng. dial.
1811 ► YATTER to speak in a constant peevish, querulous manner; to nag, to chide, to carp, to scold, to fret, to grumble; to harp on about something → Sc.
1824 ► YAP → YAUP → YAWP to speak in a chattering, nagging, or querulous way; to harp on → Sc.
1825 ► YAAG to be importunate, to insist irritatingly with questions or requests, to nag or harp on → Sc.
1827 ► YARP to grumble, to carp, to whine, to harp on something → Sc. obs.
1838 ► YABB to harp on a subject; to talk incessantly → Sc.
1875 ► RAME to dwell on a subject persistently; to whine over a grievance; to harp on about one’s troubles → Sc.
Lexicophilia 