which is correct?
(i) by-law or bye-law.
(ii) by-pass or bye-pass.

‘By-law’ and ‘bye-law’ are both acceptable. There must be a hyphen before ‘law’. A hyphen is the sigh (-) that has been used here to join by (bye) and law. A bye-law is a ‘law or regulation made by a local authority, or a corporation or a company’. The word ‘bye’ is from an Old Norse word meaning ‘town’. It is different from ‘by’ which means ‘near’. ‘Law’ is also from Old Norse which literally means something ‘laid down, fixed’. Bypass can be written with or without a hyphen. A bypass is a ‘road taking traffic round a congested area’. It also means a ‘second channel for use when the main route is blocked’. For example, in a ‘bypass surgery’, an alternative passage for the circulation of blood is provided during the operation.