Words That Do Not Gradate

In Finnish, consonant gradation is the rule, but there are several predictable groups where it does not apply or behaves differently:

• Recent Loanwords: Words borrowed from other languages that have a single medial stop (k, p, or t) usually do not undergo qualitative gradation. For example, auto (car) becomes auton, and muki (mug) becomes mukissa. However, quantitative gradation (double consonants reducing to single) IS fully productive and applies to almost all loanwords regardless of age (e.g., rokki → rokin, pankki → pankin).
• Proper Names: Qualitative gradation (e.g., k → -, p → v, t → d) is no longer productive and usually does not apply productively to new first names (e.g., Mika → Mikan, Satu → Satun). Established exceptions include Ahti → Ahdin. However, quantitative gradation (e.g., kk → k, pp → p, tt → t) is productive and applies to almost all names (e.g., Pekka → Pekan, Matti → Matin).
• Protected Clusters: A stop (k, p, t) is 'protected' and does not change if it is adjacent to certain consonants like s, or in specific mixed clusters (unlike geminates like kk, pp, tt, which do gradate). Common protected clusters include:
  - st, sk, sp: posti → postin, lasku → laskun
  - tk: matka → matkan
  - ts, ps: metsä → metsän, lapsi → lapsen
• Assimilating Clusters: While some clusters are protected, others undergo assimilation rather than simple weakening. In these cases, the stop assimilates to the preceding consonant: nt → nn (ranta → rannan), mp → mm (kampa → kamman), nk → ng (kenkä → kengän), lt → ll (ilta → illan), and rt → rr (virta → virran).
• Verbs: Gradation depends on the verb type. Type 1 verbs weaken when conjugated (e.g., nukkua → nukun), but some members of Types 3, 4, and 6 undergo inverse gradation (start weak, become strong); not every verb in these types gradates.
• Inverse Gradation in Nominals: Consonant-stem nominals (including words whose basic form ends in a consonant or historically lost one, such as hidas, koe, rengas) undergo inverse gradation. They appear in the weak grade in the nominative (dictionary) form and change to the strong grade when endings are added (e.g., hidas → hitaan, rengas → renkaan).
• Long Vowels and Diphthongs: Words ending in long vowels or diphthongs belong to word types that do not undergo gradation, regardless of syllable structure (e.g., takuu → takuun).
• Open Syllable Cases (Partitive and Essive): The Partitive and Essive cases do not close the syllable, so they do not trigger a change to the weak grade. For standard words, they remain strong (e.g., katu → katua, katuna), but distinguish the two cases for inverse-gradation words: opas → opasta keeps a weak consonant stem in the partitive, whereas essive oppaana has a strong vowel stem.
• Possessive Suffixes: Possessive suffixes use the strong vowel stem in nominative/genitive-like forms. Existing local-case stems keep their grade: kaupassamme remains weak despite -mme. For standard words, this means they remain strong even if the suffix closes the syllable (e.g., katu → katuni, kauppa → kauppamme). For inverse gradation words, adding a possessive suffix triggers a change from the weak dictionary form to the strong grade (e.g., osoite → osoitteeni).
• The Illative Case: The illative case (into) does not trigger gradation, despite closing the syllable with a consonant (e.g., kauppa → kauppaan, katu → katuun).
• Initialisms: A letter-by-letter abbreviation preserves its written letters when a case ending is added, such as alv:n. Word-like names and acronyms require their own inflectional analysis.
• Syllable Position: Gradation only happens at the boundary of the last and second-to-last syllable of the stem. In long words like teatteri, the tt is too far from the end to be affected: teatterissa.

The hk Pattern and Historical Syllables
Learn hk words individually: nahka → nahan loses k, whereas sähkö → sähkön keeps it. Traditional open/closed-syllable patterns help explain inverse gradation: rikas : rikkaan reflects a closed consonant-stem form versus a strong vowel stem. Historical final consonants have disappeared in words such as koe, and later sound changes obscure the older pattern. Use the modern paradigm instead of predicting every form from present-day syllable boundaries.