Manordeifi (Welsh: Maenordeifi) is a parish and community in the hundred of Kilgerran, in the northeast corner of Pembrokeshire, Wales. The population of the community (2001) was 478. Together with the community of Cilgerran, it makes up Cilgerran electoral ward.
In addition to scattered settlement, the parish contains the villages of Abercych and Newchapel (Welsh: Capelnewydd). There was an unusually large number of substantial mansions in the parish, perhaps because of the picturesque scenery and good angling in the area. These included Clynfyw, Ffynone (or Ffynnonau) and Pentre.
The old parish church, situated in the edge of the River Teifi floodplain at , was abandoned in favour of a new church built on the hill top in the nineteenth century. The old church (mainly 13th-14th century) preserves many old features. A coracle hangs in the porch, providing a means of escape during floods.
The population of the parish was: 745 (1801): 956 (1851): 631 (1901): 602 (1951): 402 (1981). The percentage of Welsh speakers was: 87 (1891): 94 (1931): 74 (1971).
The Ffynone estate at Boncath belonged at one time to the Morgan family of Blaenbwlan, from whom it was purchased by Captain Stephen Colby in 1752. The Ffynone mansion was built in 1795 by architect John Nash and passed down in the Colby family to John Vaughan Colby. His wife commissioned architect and garden designer Inigo Thomas to improve the house and lay out the terraced gardens. John Vaughan died in 1919 and, having no sons, left the estate to his daughter Aline Margaret, who had married C.J.H. Spence. Spence took the additional surname of Colby by royal licence in 1920 and subsequently sold the property in 1927 to a Glamorgan businessman.  The house, in 20 acres of woodland, was bought and restored from 1987 onwards by Owen Lloyd George, 3rd Earl Lloyd-George of Dwyfor and remains (2013) in the Lloyd George family.
- "National Library of Wales-Ffynone Estate Records". Arcives Wales. Retrieved 12 July 2013.
- "Ffynone". Retrieved 12 July 2013.