Derived vs. compound words

The distinction between derived and compound words is not always clearcut. The following types of words have properties of both:

• Derivations with the suffix mAinen, e.g. kidemäinen (crystal-like). The suffix is appended to the nominative of the base word, e.g. kide, instead of the inflection stem like kitee-, or to the compositive form when available, e.g. maalaismainen from maalainen.
• Derivations with the suffix lAinen denoting a person have similar properties, e.g. eläkeläinen is based on the nominative eläke, not on the inflection stem eläkkee-. However, there is some variation in this, e.g. nurmeslainen ∼ nurmekselainen, from Nurmes : Nurmeksen.
• Compound words with lainen as the second part are of different origin and mean “of the kind of…”. They have the first part usually in the genitive, e.g. kaikenlainen (of any kind), minkälainen (of what kind). In them, the second part is originally lajinen, based on laji (species, kind). In some of them, the final n of the first part has been assimilated, e.g. tuollainen, though this assimilation is not always indicated in writing, e.g. kaikenlainen may be pronounced kaikellainen. Since these words do not obey vowel harmony, at least in writing (though tällainen may be pronounced tälläinen), they are best classified as compounds.
• Words ending with moinen are similar to compounds with lainen. They mostly do not obey vowel harmony, and the first part is in the genitive, e.g. suurenmoinen, except for aikamoinen. They are logically compound words but often understood as derivations. They are treated as compounds in orthography: it has nm even though the pronunciation is [mm]. However, if the first part (stem) has only one syllable, mm is written: semmoinen, tuommoinen, tämmöinen (where the first part is tän, a short form of tämän).
• Words ending with läntä, e.g. lyhyenläntä (rather short), are best classified as compounds on similar grounds, even though läntä does not appear as a separate word.