Etymology: Cognate with Old Frisian lok , Old Dutch lok (Middle Dutch locke , Dutch lok ), Old Saxon lokk (Middle Low German locke ), Old High German loc (Middle High German loc , German Locke ), Old Icelandic lokkr , Old Swedish lokker (Swedish lock ), Old Danish lok (Danish lok ), further etymology uncertain; perhaps < the same Indo-European base as ancient Greek λύγος withy (see Lygus n.) and Lithuanian †lugnas flexible, supple. Compare also (apparently from the same Germanic base, with different stem class) Old Icelandic lykkja, Norwegian (Nynorsk) lykkje, Old Swedish lykkia (Swedish lycka), Old Danish lykki (Danish løkke), all in sense ‘bend, loop, noose’.Alternatively, it has been suggested that the sense ‘tuft’ (see sense 2) is primary and that the Germanic base is ultimately related to louk v.² In Old English a strong masculine (locc ); however, an apparent weak masculine by-form (loca , perhaps for *locca ) is attested in the sense ‘flock or tuft of wool’ (see sense 2). Whereas strong masculine locc (also not infrequently spelt loc in uninflected form) shows gemination of the stem-final consonant like its Germanic cognates, weak masculine loca (attested only in early glossaries) appears to show an ungeminated consonant; this form, if it is not simply a (recopied) scribal error, may perhaps show a genuine ungeminated n-stem derivative of the same Germanic base.

Etymology: Cognate with Old Frisian lok fastening mechanism, latch, Middle Dutch lok hole, opening, cave, Old Saxon lok closed room, also hole (in lokahti (adjective) full of holes) (Middle Low German lok hole, prison), Old High German loh hole, opening, cave (Middle High German loch hole, opening, cave, prison, German Loch ), Old Icelandic lok latch, fastening mechanism, lid (of a chest, etc.), locker, (figurative) end, conclusion, Old Swedish lok latch, fastening mechanism (Swedish lock lid), Old Danish logh (Danish låg lid), Gothic -luk (in us-luk opening), and (with different stem class) Middle Dutch loke that which shuts or encloses, enclosed area, Old Icelandic loka lock, latch, Norwegian (Nynorsk) loka latch, Old Swedish loka , luka that which shuts or closes, gate, door, hatch (Swedish lucka small door, hatch, hole, opening, Swedish regional luka latch), Old Danish laage hatch (Danish låge ) < an ablaut variant (zero-grade) of the Germanic base of louk v.¹ Compare ( < Middle English) Anglo-Norman loc latch, fastening mechanism (late 12th cent. or earlier), barrier in a waterway (late 13th cent. or earlier), and also the diminutive form loket (see locket n.²). Compare also Finnish lukko fastening, lock < early Scandinavian (compare Old Icelandic loka and the other Scandinavian forms listed above). Compare loke n.Semantic development of the base. The Germanic noun base is derived from a verbal base with the likely meaning ‘to close, lock, fasten’ (see louk v.¹), and appears to have denoted both the device or mechanism for closing and the space enclosed (compare branches I. and II.), as reflected by the variety of senses in the surviving languages, several of which developed more specific secondary senses, e.g. ‘hole, opening’. For a parallel semantic development compare locker n.¹ and classical Latin claustrum (see cloister n.). Inflectional types and semantic differentiation. In Old English two distinct words: a strong neuter (loc ) and a weak masculine (loca ), the former typically denoting the device or mechanism for closing (see sense 1), and the latter the space enclosed (see sense 9b), although there is some degree of semantic overlap. Whereas attestations of loca in the sense ‘fastening device’ are rare and clear examples are late (compare quot. lOE at sense 1a), attestations of loc in sense ‘enclosure’ are early, although clear examples in lexical (as opposed to onomastic) use are relatively rare (see sense 9a); it may be simply an accident of the historical record that loc is attested specifically with reference to enclosures for animals and loca with reference to other kinds of enclosed spaces (compare e.g. the place-name evidence discussed below). In Middle English it is difficult to distinguish the reflexes of the two Old English words. Forms such as loke, with long open ō arising from open syllable lengthening, could equally well represent reflexes of Old English loca or of oblique (disyllabic) forms of Old English loc . (The early inflected forms with final -n seen in quots. c1275 at sense 1a, c1275 at sense 9a (from the Caligula manuscript of Laȝamon's Brut) may show nunnation, a very common feature of the language of this text in this manuscript, rather than continuing weak inflection.) Use in names. Early (and widespread) currency in branch II. (specifically in sense 9) is implied by place-name evidence (the earliest attestations reflect Old English loca even when referring to animal pens); compare Cealflocan , Kent (c835; now Challock), apparently named after a pen for calves, Portlocan , Somerset (first half of the 10th cent.; also Portloc (1086); now Porlock), perhaps named for its megalithic stone circle, Horlock , Essex (1222; 12th cent. in Latin as ex duobus Orlocis ; now Harlock Cottage), lit. ‘muddy enclosure’, Pirloc , Lancashire (1228; now Parlick), lit. ‘pear-tree enclosure’, etc. The word also occurs early in surnames, but in these it can be difficult to distinguish from lock n.¹ The following appear to be local surnames and are unlikely to show lock n.¹: William de Lok (1230), Robert Atteloke (1300), Walt. ate Loke (1332). However, it is uncertain whether the sense they reflect is ‘river lock’ (see sense 10 and compare quot. 1261) or ‘animal pen, sheepfold’ (see sense 9a) or perhaps even some other kind of enclosure (see sense 9b and compare loke n.). Compare also the occupational surnames Walt. Lokward (1319), Will. le Locward (1327), which may refer to the guardian of either a river lock or an animal pen, and also Uruay le Lockhert (1203), probably referring to a herdsman in charge of a fold. Notes on specific senses. In use with reference to firearms (see sense 5) the name is due to the construction of the wheel-lock firing mechanism, which used the same parts as a contemporary fastening mechanism operated with a key. This sense development is paralleled in etymologically unrelated words meaning ‘lock’ in other languages (e.g. Dutch slot (1562 in vuurslot firelock; compare slot n.¹) and Swedish lås (1548 with reference to firearms)). With use with reference to rowing (see sense 6) compare earlier oarlock n. and rowlock n.¹ With use with reference to animal pens (see sense 9a) compare the Old English compound loc-hyrdel hurdle for a sheepfold, and also post-classical Latin lokium enclosure, fold (1267 in a British source in this sense) and locclaia , locclata , locclatis hurdle for constructing a pen (frequent in the 14th cent. in British sources; compare clate n.). Earlier currency with reference to barriers (originally flash locks) on waterways (see sense 10) is implied by post-classical Latin loccum (from 1190 in British sources in this sense, apparently earliest with reference to the River Lea or Lee, Essex); compare also the minor place names Wrinelelocke and Brokesburnlock , Essex (both 1270, apparently barriers on the River Lea; compare quot. 1277 at sense 10, also with reference to the same river). The origin of uses with reference to the Lock Hospital in Southwark (see sense 15) is uncertain; it was probably so called on account of being specially isolated or quarantined, and some early sources discuss the security of the hospital and the need for inmates to be kept out of the city. An alternative suggestion that the name is derived from Middle French loque rag ( < Dutch locke lock n.¹), with reference to the rags with which the sores of lepers were dressed, seems less likely and cannot be substantiated.