Thanksgiving UK [ˈθæŋksˌɡɪvɪŋ] / US or Thanksgiving Day UK / US noun [countable/uncountable]
Word forms "Thanksgiving":
singular Thanksgiving plural Thanksgivings
Word forms "Thanksgiving Day":
singular Thanksgiving Day plural Thanksgiving Days
a) in the US, the fourth Thursday in November, and in Canada, the second Monday in October, when families have a special meal, traditionally to celebrate all the things that they are grateful for

Will you be seeing your family on Thanksgiving?

a Thanksgiving dinner

b) in the US, the holiday period of four or five days that includes this day

Are you going home for Thanksgiving?

English dictionary. 2014.