Lenition - Synchronic Lenition - Blocked Lenition

Blocked Lenition

Some languages which have lenition also have complex rules affecting instances of where lenition might be expected but does not occur. Such instances often involve homorganic consonants. In Scottish Gaelic for example there are 3 homorganic groups:

• d n t l s (usually called the dental group in spite of the non-dental nature of the palatals)
• c g (usually called the velar group
• b f m p (usually called the labial group

In a position where lenition is expected due to the grammatical environment, lenition tends to be blocked if there are two adjacent homorganic consonants across the word boundary. For example:

• aon 'one' (which causes lenition) → aon chas 'one leg' vs aon taigh 'one house' (not aon *thaigh)
• air an 'on the' (which causes lenition) → air a' chas mhòr 'on the big leg' vs air an taigh donn 'on the brown house' (not air an *thaigh *dhonn)

In modern Scottish Gaelic this rule is only productive in the case of dentals but not the other two groups for the vast majority of speakers. It also does not affect all environments any more, for example while aon still invokes the rules of blocked lenition, a noun followed by an adjective generally no longer does so. Hence:

• ad 'hat' (a feminine noun causing lenition) → ad dhonn 'a brown hat' (although some highly conservative speakers retain ad donn)
• caileag 'girl' (a feminine noun causing lenition) → caileag ghlic 'a smart girl' (not caileag *glic)

The is a significant number of frozen forms involving the other two groups (labials and velars) and environments, especially in surnames and place names:

• MacGumaraid 'Montgomery' (mac + Gumaraid) vs MacDhòmhnaill 'MacDonald (mac + Dòmhnall)
• Caimbeul 'Campbell' (cam 'crooked' + beul 'mouth') vs Camshron 'Cameron' (cam + sròn 'nose')
• sgian-dubh 'Sgian-dubh' (sgian 'knife' + dubh '1 black 2 hidden'; sgian as a feminine noun today would normally cause lenition on a following adjective) vs sgian dhubh 'a black knife' (i.e. a common knife which just happens to be black)

Though rare, in some instances the rules of blocked lenition can be invoked by lost historical consonants, for example in the case of the past-tense copula bu which in Common Celtic had a final -t. In terms of blocked lenition it continues to behave as a dental-final particle invoking blocked lenition rules:

• bu dona am biadh 'bad was the food' vs bu mhòr am beud 'great was the pity

Blocked lenition phenomena are also known to occur in Irish and Spanish (orthographic b d g retained as /b/, /d/, /ɡ/ following nasals rather than their normal lenited forms ).