The second declension has the following characteristics:—
(1) The partitive sing. ends in -a or -ä (-ta, -tä) after a short vowel. (Polysyllables have often -ta, -tä.)
(2) The nominative has the same number of vowels as the root, and generally preserves those vowels unaltered except that the final a or ä of comparatives and final e become i.
(3) The illative sing. ends in the last vowel of the root doubled with n suffixed; kirkkoon, not kirkohon.
(4) The genitive plur. generally ends in -jen or -en, as described above. In the ordinary language this -en is further weakened to -in after the vowel of the root, unless that vowel is itself i.
(5) Hard consonants at the beginning of the last syllable are of course softened by rules [24-35], when the syllable becomes closed.
This declension comprises—
A. Roots ending in the vowels o, ö, u, y, which never change.
Example:—Aurinko, the sun.