We have been talking about some of the stronger characters in the Gaelic alphabet, this week we are going to look a weaker character; the letter F. 
F only makes one sound regardless of whether it is broad or slender and that is the F sound we are used to in English. 
When it is lenited is looses all its sound, it just gives up and makes no sound at all. 
And, it will lenite at the drop of a had. Really f will lenite when no other letter will. 
Any word that has a lenited F in the front of it should be treated as if it begins with the letter that follows the lenited F. 
For feminine nouns that begin with F the definite article would like to be a' +lenition but when F lenites and the sound goes away that doesn't work anymore because you end up with two vowel sounds together, so the article changes to an + lenition. 

We have been talking about some of the strong characters in the Gaelic alphabet and S is another one of these. Though not as strong a lenition resister S will resist lenition is some cases and she is often grouped with T and D. She also will not lenite when she is hanging out with G,P,T (sg,sp,st). When she does lenite she makes a H sound. When combined with the definite article an t- her sound will be overridden by T and he will be broad or slender in relation to the vowel on the other side of the S. When broad she makes the normal S sound and when slender she makes the SH sound.  
​There is also a tendency in Gaelic to do pairs of words with opposite meanings where the words sound the same but one starts with S and the other with D.
​for example: saor=free/inexpensive  daor=expensive