This page is from http://www.stooryduster.co.uk a web site where you will find many Scottish Words illustrated and defined with translations into English. There is help with pronunciation, quizzes, recipes, poems and every week there is a new word and a new illustration. You can search for words or sort the illustrations by category. It's not yet an illustrated dictionary but it's heading that way.
“Wirm” sounds a bit English, actually. I remember an English biology teacher at my Edinburgh school writing the following on the blackboard, to accompany an illustration: “This is a wrm. Not a wurrum.”
I pronounce it like your enlightened teacher where the vowel is hardly sounded at all. Unlike the poshest English pronunciation with two marbles in the mouth where the vowel sound ends up longer than the whole of the rest of the word. weuuuurm.