I’ll register some confusion at Robert Semple’s answer that it’s a day labourer; I’ve read Crossan too, and I don’t remember that.
I’m not disputing it; Crossan is pretty dense.
What’s stuck in my head is what the Jesus Seminar decided (and Crossan was a prime move behind it, but not the only one): they were inclined towards interpreting it as “builder”, because of the number of building references in Jesus’ parables and sayings (capstone, not a stone upon a stone, etc).
Note that the Greek word used in the Gospels, tektōn, shows up in English: archi-tect (literally chief tektōn), tectonics.