lakh / loch / lock / lough are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
lakh: NA
loch: (noun) a long narrow inlet of the sea in Scotland (especially when it is nearly landlocked). (noun) Scottish word for a lake.
lock: (noun) a fastener fitted to a door or drawer to keep it firmly closed. (noun) a strand or cluster of hair. (noun) a mechanism that detonates the charge of a gun. (noun) enclosure consisting of a section of canal that can be closed to control the water level; used to raise or lower vessels that pass through it. (noun) a restraint incorporated into the ignition switch to prevent the use of a vehicle by persons who do not have the key. (noun) any wrestling hold in which some part of the opponent's body is twisted or pressured. (verb) fasten with a lock. (verb) become rigid or immoveable. (verb) hold in a locking position. (verb) hold fast (in a certain state). (verb) pass by means through a lock in a waterway. (verb) build locks in order to facilitate the navigation of vessels.
lough: (noun) a long narrow (nearly landlocked) cove in Ireland. (noun) Irish word for a lake.
lakh: NA
loch: l·AA·k
lock: l·AA·k
lough: l·AW
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)