Is at syne an irregular verb?
at synes is, the infinitive is the same as the present, I have a feeling it has been derived from the passive form of at syne, which is pretty regular and, according to Wiktionary is more along the lines of "to inspect/examine" or can be seen
Hvad er du, ti?
I get confused about the difference between "kedelig" meaning boring and "ked" meaning sad. Jeg er ked af det. I am sorry about it.