Probably from Swedish rask (“fast, brisk”).

• IPA^(key): /ˈrɑski/, [ˈrɑ̝s̠k̟i]
• Rhymes: -ɑski
• Syllabification^(key): ras‧ki
• Hyphenation^(key): ras‧ki

raski

1. a fermentation starter used in the leavening of (sourdough) rye bread

• leipäjuuri

• “raski”, in Kielitoimiston sanakirja [Dictionary of Contemporary Finnish]‎^[1] (in Finnish) (online dictionary, continuously updated), Kotimaisten kielten keskuksen verkkojulkaisuja 35, Helsinki: Kotimaisten kielten tutkimuskeskus (Institute for the Languages of Finland), 2004–, retrieved 1 July 2023

From Swedish rask.

• IPA^(key): /ˈrɑski/, [ˈrɑ̝s̠k̟i]
• Rhymes: -ɑski
• Syllabification^(key): ras‧ki
• Hyphenation^(key): ras‧ki

raski

1. a thin woolen twilled fabric; cloth rash

• IPA^(key): /ˈrɑski/, [ˈrɑ̝s̠k̟i] (third-person indicative)
• IPA^(key): /ˈrɑskiˣ/, [ˈrɑ̝s̠k̟i(ʔ)] (imperative, indicative connegative)
• Rhymes: -ɑski
• Syllabification^(key): ras‧ki
• Hyphenation^(key): ras‧ki

raski

1. inflection of raskia:
   1. third-person singular past indicative
   2. present active indicative connegative
   3. second-person singular present imperative
   4. second-person singular present active imperative connegative

• karsi, raksi, rikas, riksa