noun
golden wedding anniversary; 50th wedding anniversary
Refers specifically to the celebration or ceremony marking 50 years of marriage.
両親の金婚式に家族が集まった。
The family gathered for my parents' golden wedding anniversary.
銀婚式 is the 25th wedding anniversary, while 金婚式 is the 50th.
Compound of 金 (kin, 'gold') + 婚 (kon, 'marriage') + 式 (shiki, 'ceremony'). The term follows the Western tradition of naming wedding anniversaries after precious materials.