I can't find this word in Dinneen's. Does anyone know anything about the origin or what spelling it would be under in Dinneen's? I can't wait for the Digineen project to be finished!

Perhaps under 'ambasa'?

Níl an Duinníneach le mo thaobh anois a Josh, ach b'fhéidir gurbh fhiú féachaint faoi 'ambasa'?

'dom baiste' a shamhlaím féin leis, ceart nó contráilte.
(Ní shéimhítear an 'b' mar gheall ar chomhghaol consan; homogenous consonants give the séimhiú a shove here)

Thanks. After reading your post, I found it under ambasa and under bas.

'Ambasa' may be preferred in Cork.

Thats the thing about Dinneen (a bit) and Ó Donaill (a lot) is that when I tried to make a start on a root dictionary, it was so big you ended up with words whose root had changed or had a different spelling or (de)voiced etc. Very often I had the same experience when I came across a word with slender spelling and not broad etc

tagann an foclóir Beag le thuairim Sheosaimh:

ambaiste [intriacht]
dar mo bhaiste.