yhdys- (“connected, combined, united”) +‎ sana (“word”). Coined by Finnish folklorist and linguist Daniel Europaeus in 1853.

• IPA^(key): /ˈyhdysˌsɑnɑ/,
• Rhymes: -ɑnɑ
• Hyphenation^(key): yhdys‧sana

Finnish Wikipedia has an article on:

yhdyssana

Wikipedia ^fi

yhdyssana

1. (grammar) compound word, compound, often: compound noun

• In Finnish spelling, all compounds are spelled as closed compounds or hyphenated compounds, so the term yhdyssana is often erroneously used to only refer to closed or hyphenated compounds in English, and the term sanaliitto (whose correct meaning is phrase, set phrase, or fixed phrase) is often erroneously used to refer to English open compounds.
• In Finnish spelling, compounds will be hyphenated under certain conditions (see the rules described here).

• määriteosa
• perusosa

• “yhdyssana”, in Kielitoimiston sanakirja [Dictionary of Contemporary Finnish]‎ (in Finnish) (online dictionary, continuously updated), Kotimaisten kielten keskuksen verkkojulkaisuja 35, Helsinki: Kotimaisten kielten tutkimuskeskus (Institute for the Languages of Finland), 2004–, retrieved 2023-07-04