ONlwSG

udrathad m. [ˈud̪̥ ̩ ɾa-əd̪̥], -[ ̩ ɾa-ad̪̥], 

Or [ˈu̟]-.

gen. -rathaid -[ɾa-id̥ʲ], -[ɾɔ-id̥ʲ], ‘by-road etc.’ has a number of forms:

A. SG udrathad, ùdrathad
A 1. SG udrathad [ˈud̪̥ ̩ ɾa-əd̪̥], -[ ̩ ɾa-ad̪̥]
In M^cAlpine 1832: [ŭdd´-ră-ad] ‘free egress’.

A 2. SG ùdrathad [ˈuːd̪̥ ̩ ɾa-əd̪̥], -[ ̩ ɾa-ad̪̥]
(i) ùdrathad (HSS 1828: ‘free egress and regress to common pasture’; MacBain 1896: ‘idem’; Dwelly 1911: ‘free egress and regress to common pasture; common road to common grazing, peats etc.’; MacLennan 1925: ‘[ootraj] ... “free egress and regress to common pasture; any road leading in from main road”, also and commonly ùtraid [B 2(ii)]’);
(ii) ùghdrathad (Dwelly 1911: see ùdrathad).

B. SG utraid, ùdraid, ùtraid
B 1. SG utraid [ˈuʰt̪ɾɑd̥ʲ], ?utrad [ˈuʰt̪ɾɑd̪̥]
(i) utraid (Shaw 1780: ‘a way for cattle’);
(ii) utrod (Armstrong 1825: ‘a cattle road’; Dwelly 1911: see ùdrathad).

B 2. SG ùdraid [ˈuːd̪̥ɾɑd̥ʲ], ùtraid [ˈuːʰt̪ɾɑd̥ʲ]
(i) ùdraid (Faclan bhon t-Sluagh^˄: [u̟:d̪ɾɑdʹ] ‘a township road’, North Uist);
(ii) ùtraid (HSS 1828: see udrathad [leg. ùdrathad]; MacBain 1896: ‘free egress and regress to common pasture’; CG VI, 144: ‘by-road, cattle-road’; Dwelly 1911, see ùdrathad; MacLennan 1925: ‘side-road, branch-road serving a village’; AFB^˄: ‘access road to common land’, Western Isles, Tiree; Faclan bhon t-Sluagh^˄: [u̟:t̪ɾɑdʹ] ‘track to permit the passage of cattle to the common grazings, between crofts or townships’, Tiree);
(iii) ubhtraid (Dwelly 1911: ‘service road in a township, especially one branching off a main road’, Uist, see ùdrathad);
(iv) ughtraid (Dwelly 1911: ‘side-road off a highroad’, see ùdrathad);
(v) ughdaraid (Faclan bhon t-Sluagh^˄: ‘a track or path used by cattle’, South Uist).

For SG ùdrathad and ùtraid, MacBain (1896; 1911) compares ON útreið f. ‘expedition (usually to battle)’ (lit. ‘out-riding’), so also Henderson (1910, 117); 

As does Angus Matheson (CG VI, 144).

MacLennan (1925, s.v. ùtraid) suggests a derivation from ON útarr ‘outer’ + stræti ‘street’; while McDonald (2009, 425) suggests a compound of ON útarr + SG rathad ‘road’. Noting that a derivation from útarr + stræti is phonetically implausible and that a development from útreið is also semantically weak, Cox (2007b, 69) proposes a loan-blend from Scots outroad, ootroad ‘the road that leads away from home’ (SND^˄), with forms under (A) assimilated to Gaelic rathad; 

EG (disyllabic) roüt (Cox 2002a, 206; Oftedal 1956, 54: (rout); see also Clancy 2007).

for variation in the length of the stressed vowel, cf. SG udabac ~ ùdabac (s.v.).