Scots Gaelic has — like many other languages — verbs that are not conjugated in all forms. These verbs are called defective.

For instance, the following Scots Gaelic verbs are defective:

• arsa (only past)
• faod (only present and conditional)
• siuthad (only imperative)
• thalla (only imperative)
• theab (only past)
• trobhad (only imperative)
• tàrlaidh (no present)