Assalaam Alaikum,

Ibn 'Abd as-Salaam said: I have not come across any definition of major sin that could be completely free of some flaws. The best is to define it as any sin that could indicate that the level of negligence of the one who commits it is like the level of negligence of one who commits the least of the major sins mentioned in the texts. Some defined it as any sin that is accompanied by a warning of punishment or being cursed.

Ibn as-Salaah said: Major sins have indications such as the stipulation of hadd punishments for such acts; a warning of punishment in Hell and the like in the Qur'an or Sunnah; a description of the doer as an evildoer; and mention of a curse upon the one who does it.

Ismaa'eel al-Qaadi narrated, with a sound chain of narration from al-Hasan al-Basri, that the latter said: Every deed concerning which Allah, may He be exalted, warned the doer of Hell is a major sin.

Major sins:

Worshiping others, or associating partners with Allah (shirk) believing in superstition, fortune telling, and astrology (includes believing in horoscopes and palmistry, etc) Using magic or sorcery, committing murder, committing suicide, bearing false witness, c ommitting adultery or fornication, cheating, stealing, and lying, charging or paying interest or usury (riba) , consuming pork or alcohol, consuming the wealth of an orphan , not fasting for Ramadan, not observing daily prayers, not paying zakat (annual charity), gambling, oppression annd unjust leadership, bribery, betraying trusts and breaking contracts, backbiting and slandering, breaking the ties of kinship, disobeying or not honouring one's parents

  {If you avoid the great sins which you are forbidden to do, We shall expiate from you your (small) sins} [An-Nisa': 31].

I've been trying to find examples of minor sins but I can't seem to find any, but I think it may include lying or other minor sins that are committed daily.