A. Those which are used as postpositions only in one case, and which have become more or less petrified. Such are ennen, before; ilman, without; kanssa, with; varten, for.
B. Those which are used in several cases. Some of these are ordinary substantives used in the nominative and other cases. The postpositional usage of such words corresponds to such English phrases as ‘in the middle of.’ Such are joukko, a crowd; (joukossa, joukkoon); jälki, a footstep (jälessä, jälestä, jälkeen); kohta, a place (kohdalla, kohdalta, kohdalle, kohtaan); puoli, a half (puolessa, puolesta, puolella, puolelta, puoleen); pää, a head (päässä, päästä, päähän, päällä, päälle, päältä).
Others, though clearly substantives in their form, are not used except as particles:—yli, ylitse, yllä, ylle, yltä; ympäri, ympärillä, ympäriltä, ympärille; alla, alta, alle; edessä, edestä, eteen, edellä, edeltä, edelle; luota, luona, luo; ohessa, ohesta, oheen, ohitse; myötä, myöten, and others.
THE ADVERB.
There are two classes of adverbs in Finnish: (1) Independent adverbs, (2) Adverbial suffixes.
The independent adverbs are often cases of nouns which differ from postpositions only in this, that they are used absolutely, and not in connection with another word. Thus in käydä kaupungin ympäri, to go round the town, ympäri may be described as a postposition, while in käydä ympäri, where it stands alone and absolute, it is an adverb. Similarly in kulkea puutarhan ohitse, to pass by the garden, ohitse is a postposition, but in pian se menee ohitse, it will soon be over, it is an adverb.
These independent adverbs are formed in different ways:—
A. Some are primitive words, whose grammatical formation is not clear, e.g. nyt, now; heti, soon; aina, always; vielä, yet; koska, when.
B. A second class is formed by the addition of certain suffixes.