Beyom = when.  It is the figure Synecdoche, by which a part is put for the whole, or the whole for a part (see Ap. 6).  What that "part" is must be determined by the context in each particular case.

• In Gen. 2:4, it is put for the whole six days.
  
  
• In Num. 7:84, it is put for the whole twelve days of the dedication of the altar.
  
  
• In Lev. 13:14, it is rendered "when".  R.V. whensoever.  Num. 28:26, see notes.
  
  
• In Lev. 14:57, it is rendered "when", both in A.V. and R.V.  Cp. Deut. 21:16.  1Sam. 20:19.  2Sam. 21:12.
  
  
• In 1Kings 2:37, it is rendered "on the day", but v. 41 shows that Shimei had been to Gath and back before Solomon executed the sentence (vv. 37, 42).
  
  
• In Ps. 18:18, it is rendered "in the day", but evidently means at the time when.
  
  
• In Isa. 11:16, it includes the whole period of the Exodus.
  
  
• In Jer. 11:4, 7, it includes the Exodus and the whole time of giving the law at Sinai.  Cp. ch. 7:22; 31:32; 34:13.
  
  
• In Ezek. 20:5, 6 (*1), it includes the whole time of God's choice of Israel.
  
  
• In Ezek. 36:33, it includes the whole time of rebuilding the waste places of Israel in the future restoration.  Cp. ch. 38:18 (*2).  A.V. = at the same time.  R.V. = in that day.

(*1).  In verse 6 it has the definite article (bayom), and denotes the specific day when Jehovah delivered them, in contrast with the indefinite past time of His choice.

(*2).  Here the definite article is used to mark a specific occasion.  See A.V.