EVENing

evening 

from O.E. æfnung "evening, sunset," verbal noun from æfnian "become evening, grow toward evening," from æfen "evening" (see eve). As a synonym of even (n.), it dates from mid-15c. and now entirely replaces the older word in this sense. Another O.E. noun for "evening" was cwildtid.

1. (n.) evening
the latter part of the day and early part of the night.

2.  evening
the period from sunset to bedtime.

What time do you think evening ends?

Try and figure it out, you'll be surprised.

twilight 

late 14c. (twilighting), a compound of twi- + light (n.) Cognate with Du. tweelicht (16c.), Ger. zwielicht. Exact connotation of twi- in this word is unclear, but it appears to refer to "half" light, rather than the fact that twilight occurs twice a day. Cf. also Skt. samdhya "twilight," lit. "a holding together, junction," M.H.G. zwischerliecht, lit. "tweenlight." Originally and most commonly in English with reference to evening twilight but occasionally used of morning twilight (a sense first attested mid-15c.). Figurative extension is first recorded c.1600.