=== SPOILER WARNING - SPOILER WARNING - SPOILER WARNING ===
I'd suggest the following definition for dwarfy:
Requirements:
It must not be the simplest solution to the problem, but it must solve it (note that omnicide is ALWAYS a valid solution).
It must either take a lot of resources (dwarves, time, stone, magma, blood, etc) OR a lot of ingenuity to implement.
It must lie towards the megalomaniacal/evil end of the grandure/ethical spectrum.
Bonus points:
Involvement of magma.
Involvement of stupidly rare/valuable/unethical substances such as slade, adamantine, forgotten beast body parts, blood, mermaid bones, etc.
Killing large numbers of dangerous/cute/good creatures. The more the better.
Needless size - why build a 15 z-level death shaft when you can build a 200 z-level one with magma-falls down the inside?
Needless cruelty, especially to sentients - see mermaid farming.
Ridiculous location - why build that temple to Armok 2 levels underground when you could build it 100 z levels in the sky, or under the magma ocean, or even in hell.
Epic bravery - send a single champion into the pits of hell wielding only a charred elf skull. He'll probably die, but if he survives it will be EPIC!
Needless disregard for nature - sure, the trees look pretty, but they'd look much more DWARVEN under 10 z-levels of magma.