Síneadh fada literally means "a long stretch" and when a síneadh fada occurs over a vowel it shows that the vowel is long rather than short.
This difference can indicate distinct meanings:
Examples of words with short vowels: fear (a man) and cas (turn)
- Examples of words with long vowels: féar (grass) and cás (a case).
The only difference in writing between these pairs of words is whether or not the vowels have a síneadh fada. This is an important difference, as it may affect the meaning.
The plural of síneadh fada is sínte fada "length marks".