Fondue is a Swiss

Swiss cuisine

Swiss cuisine bears witness to many regional influences, including from Italian, French, and German cuisine, and also features many dishes specific to Switzerland...

 dish of melted cheese served in a communal pot (caquelon

Caquelon

A Caquelon is a cooking vessel of stoneware, ceramic, enamelled cast iron, or porcelain for the preparation of fondue.The word is from a Swiss French term originating in the 18th century derived from the Swiss German word Kakel meaning an earthenware casserole...

) over a spirit lamp (rechaud), and eaten by dipping long-stemmed forks with bread into the cheese. It was promoted as a Swiss national dish by the Swiss Cheese Union in the 1930s and became popular in North America in the 1960s.

Since the 1950s, the name "fondue" has been generalized to other dishes where a food is dipped into a communal pot of hot liquid: chocolate fondue, where pieces of fruit are dipped into a melted chocolate mixture, and fondue bourguignonne, where pieces of meat are cooked in hot oil.
The word fondue is the feminine passive past participle

Participle

In linguistics, a participle is a word that shares some characteristics of both verbs and adjectives. It can be used in compound verb tenses or voices , or as a modifier...

 of the French verb fondre ('to melt') used as a noun, probably influenced by a Franco-Provençal

Franco-Provençal language

Franco-Provençal , Arpitan, or Romand is a Romance language with several distinct dialects that form a linguistic sub-group separate from Langue d'Oïl and Langue d'Oc. The name Franco-Provençal was given to the language by G.I...

 word.