In order to understand a Finnish word, you need to recognize its structure. Normally you start from the end and try to recognize suffixes, then see if the remaining word can be recognized or found in a dictionary. If it is long, it might be a compound word. So some general knowledge is needed to analyze e.g. the word form puhelinnumerosi. You would first recognize si as a possible possessive suffix, then notice that there is nothing suffix-like before it, and finally try to interpret puhelinnumerosi as a compound.
The suffix glossary in this book may be of help in recognizing words as derived words or as inclined forms.
There are various word analyzer programs, which take a word form as input and display one or more ways to decompose it into components.
It is quite possible that a word form has several interpretations, several “parse trees”. For example, kannat can be a plural form of the noun kanta (base) but also a 2nd person singular form of the verb kantaa (to carry). Analyzers usually show the different interpretations.
On the other hand, a word form might be ambiguous only in a hypothetical sense. For example, by its form only, ojennat could be a form of the verb ojentaa (to stretch out), or a form of the noun ojenta or ojenna—but such nouns do not actually exist. Analyzers normally use a word data base to exclude possibilities that are not real. This also means that an analyzer may fail to show an analysis when it involves a word that is not its database due to being too new, too rare, dialectal, or colloquial.
Oikofix is a free online service, available at oikofix.com. It is based on voluntary work and still under development, but very useful. It can be used to spellcheck Finnish (or English) text, submitted as plain text, but also to perform morphological analysis.
Oikofix has alternative user interfaces in Finnish and in English. The screen shot below is from the English version.
The user interface is somewhat special. Instead of entering text and then selecting a function, you need to
You select the analysis mode by clicking on the button “Read and analyze texts” (Lue ja analysoi tekstiä) on the left. Then type or paste text in the large text area and click on the button “Analyze” (Analysoi teksti), which then changes to “Continue editing” (Jatka tekstin muokkausta), shown in the screenshot above. After this, click on any word in your text to get an analysis of it; the screenshot above shows an analysis of the word haluat.
The HFST analyzer is a multilingual word analysis software. It requires a formal morphological description of a language, and there is such a description for Finnish as well as for a large number of other languages. It is an academic activity rather than a common practical tool, so the user interface is clumsy.
To use it, enter the word or text in text area provided, select Finnish from the language menu, and click on “Process wordform”. There are two alternative display formats, selectable from a dropdown: “CG/TWOL analysis sets” (the default) uses a notation like “haluta+V+Act+Ind+Prs+Sg2”, whereas “Apertium style analyses” uses a notation with “<” and “>” symbols as shown in the screenshot below. The notations are briefly explained on the page jkorpela.fi/omorfi-en.html.
There is an alternative service based on the same technology, at the University of Tromsø: giellatekno.uit.no/cgi/d-fin.eng.html.