Publishing history:v1.0
v1.0: 25/02/25
ceap m. [kʲʰɛʰp], gen. cip [kʲʰiʰp], ‘block; last’ is derived by Craigie (1894, 157; 
Craigie gives SG ceap, ceapa. The form ceapa is recorded in the open compound ceapa caoil ‘a bundle of willow wands for making a creel’ (Faclan bhon t-Sluagh˄: Skye (fn 7, below)), but final -a -[ə] here is likely to be epenthetic and the result of euphony. The same source records SG ceapa làir ‘turfing-spade’ for Skye and ceapa làr [kʹe̱b̥ə ɫɑ̟:ɾ] ‘idem’ for North Argyll, but this seems to be the result of confusion (at some level) of ceap with SG ceaba, ceibe, caibe ‘spade’.
so also de Vries 1962) from ON keppr m. ‘stick, cudgel’. McDonald (2009, 371) considers the loan likely.
McDonald notes Marstrander’s (1932, 280) derivation of the Isle of Man place-name Keppel from ON *Keppafjall ‘(the) mountain of the sticks’ (so also Broderick 1984 IV, 402). However, simply from its occurrence in an Old Norse loan-name it cannot be inferred that ON keppr was also borrowed into Manx (pace de Vries 1962, s.v. keppr).
SG ceap and Ir. ceap 
‘Stock; block, base; pad etc.’ (Ó Dónaill 1977), and cf. phrases such as Ir. (d’imigh siad) ina gcip is ina gcóiste, the equivalent of Eng. (they left) lock, stock and barrel (pers. comm. Professor Seòsamh Watson).
go back to OG cepp ‘tree-stump, log, block; anvil-block; stocks, pillory’ (eDIL˄), itself from Lat. cippus ‘pale, stake’ (MacBain 1911; Marstrander 1915a, 121; 
McDonald (2009, 371) remarks that Marstrander fails to explain why he argues for a Latin as opposed to an Old Norse derivation: it is partly a question of chronology: OG cepp is attested in the 9th-century (Book of Armagh, in Stokes and Strachan 1901–10 I, 497.27: icip; Sanas Cormaic: Early Irish Glossaries Database˄, s.v. grith Y.690: don c[h]ip – for the dat. sg. form cip, see Mc Manus 1983, 37 + fn 37).
eDIL˄; Vendryes 1996).
While the primary sense of SG ceap is ‘block, stock or lump of some material’, 
Shaw 1780; Mac Farlan 1795; MacFarlane 1815; Armstrong 1825; HSS 1828; MacEachen 1842; Dwelly 1911; AFB˄.
it has a number of extended senses: ‘a block of material used in the construction of articles or performance of tasks, e.g. a shoe last, 
Shaw 1780; Mac Farlan 1795; MacFarlane 1815; Armstrong 1825; HSS 1828; McAlpine 1832; MacEachen 1842; Dwelly 1911; Faclan bhon t-Sluagh˄; AFB˄.
a creel-making frame or basket-weaver’s template 
Faclan bhon t-Sluagh˄; AFB˄. Cf. SG ceap-sgiath ‘wool-winder’ (Faclan bhon t-Sluagh˄). As for Faclan bhon t-Sluagh˄’s ceapa caoil ‘a bundle of willow wands for making a creel’ (fn 1, above), the sense ‘bundle’ may be an extension of either ‘block, lump’ or ‘weaver’s template’.
’; ‘a block for restraining an animal’s movements, a stumbling-block’; 
McAlpine 1832; Dwelly 1911. Cf. SG ceap-starra ‘threshold, doorsill’, also ‘obstruction’ (cf. SG cnap-starra ‘obstruction’) (Faclan bhon t-Sluagh˄).
‘a trap, gin, snare’; 
HSS 1828; McAlpine 1832; MacEachen 1842; Dwelly 1911.
‘bilboes (shackles)’; 
Dwelly 1911.
‘(punishment) stocks’; 
MacDomhnuill 1741; Shaw 1780; MacFarlane 1815; Armstrong 1825; HSS 1828; McAlpine 1832; Dwelly 1911; McDonald 1972; AFB˄.
‘a block of turf or peat, a sod’; 
McDonald 1972; Faclan bhon t-Sluagh; AFB˄.
and ‘a seat made from turves’. 
Dwelly 1911; Faclan bhon t-Sluagh˄.
However, the senses ‘cap’ 
Armstrong 1825; McAlpine 1832; MacEachen 1842; Dwelly 1911; Faclan bhon t-Sluagh˄; AFB˄.
and, by extension, ‘skull cap’, 
HSS 1828.
‘wheel nave’, 
Dwelly 1911.
‘cap for a muzzle-loading gun’ 
Faclan bhon t-Sluagh˄.
and ‘abomasum (a sheep’s fourth stomach)’ 
Faclan bhon t-Sluagh˄; AFB˄.
most likely come from Scots kep [kɛp] [kep] [kæp] [kjɛp] ‘cap, covering for the head’ (SND˄), while the senses ‘top, as of a hill’, 
Armstrong 1825; Dwelly 1911.
‘rallying point in battle’ 
Shaw 1780; Armstrong 1825; HSS 1828; Dwelly 1911.
and ‘cape’ 
AFB˄.
probably come from Scots caip [kep] [kɑp] ‘the highest part of anything; a coping’ (SND˄). Finally, the senses ‘head; stock’ 
Shaw 1780; Armstrong 1825; Dwelly 1911.
(although not quite clear) and ‘(knee) cap’ 
Faclan bhon t-Sluagh˄: ceap na glùineadh.
may come from either Scots kep or Scots caip.
Derivatives: SG ceapach ‘tillage plot’, with the suffix -ach, anglicised in place-names as Keppoch (e.g. Watson 1904, xxxiv, 101, 144, 170, 248); the diminutives ceapag ‘small turf, sod’, with the suffix -ag, and ceapan ‘little last or stock’, with the suffix -an (e.g. MacLennan 1925).
In Irish, cf. (≈Ó Dónaill 1977) ceapóg ‘a little tillage plot; seed-bed; level patch of ground; planting-stick, dibble’; ceapach ‘tillage plot; flower/vegetable-bed’ (and, by extension, ‘territory’ (Dinneen 1947)); and cipín ‘little stick’, cipín solais ‘match, lucifer’.