ferie (holiday)

fejring (celebration)

fødselsdag (birthday)

Jul (Christmas)

Påske (Easter)

Nytår (New Year)

Halloween (Halloween)

Thanksgiving translates to "Thanksgiving" or "Høsttakkefest" in Danish, with the latter more directly referring to a harvest thanksgiving celebration, though it's not a traditional Danish holiday. (Thanksgiving)

festival (festival)

optog (parade)

fyrværkeri (fireworks)

tradition (tradition)

fest (party)

kostume (costume)

dekoration (decoration)

gave (gift)

gave (present)

invitere (invite)

vært (host)

festmåltid (feast)

højtiden (holiday season)

lykønskningskort (greeting card)

ceremoni (ceremony)

genforening (reunion)

ferie (vacation)

national helligdag (national holiday)

helligdag (public holiday)

karneval (carnival)

årsdag (anniversary)

fejre (celebrate)

dekorere (decorate)

samle (gather)

udveksling (exchange)

ære (honor)

iagttage (observe)

ritual (ritual)

skik (custom)

mindelse (memory)

lejlighed (occasion)

begivenhed (event)