One word for "tedious" and "intellectually challenging"

Question

I am looking for a single word that implies that something was tedious to do, but was also intellectually challenging. For example, filling out legal forms may be quite tedious, but perhaps it can be intellectually challenging to discern how the content of a form interacts with the law.

I can't seem to find a word that encompasses such a meaning. I considered "toilsome", but I don't think this implies the type of intellectual work that I am looking to describe. "Arduous" falls into the same boat...

A sample sentence would be, "I found the task to be quite Word_Here."

Answer 1

Stressful — ODO

adj. causing mental or emotional stress
"corporate finance work can be stressful."

Answer 2

I settled on "herculean."

I like the definition

"not easy; requiring great physical or mental effort to accomplish or comprehend or endure"

because it implies that something was both difficult to do/endure, and that it required "great mental effort" to comprehend.

Answer 3

It doesn't provide the precise connotations of requiring endurance and intellect, but an apt word may be onerous:

: difficult and unpleasant to do or deal with
_{Merriam-Webster}

Answer 4

I found this question while trying to find the word for a PERSON who is intellectually tedious, like a professor that over explains or a book that writes in 20 pages what could be said in one page. Like over-intellectualizing.

• Belaboring - top choice so far
• Bloviating - second choice so far
• Labored - third choice so far
• Pedantic - fourth choice because it sounds more intellectual than tedious
• Pretentious - fifth choice so far because is sounds like it is fake and tedious instead of intellectual and tedious

A couple of words that could stand as the Person. For example. He just loves being "magniloquent". He is being something rather than doing something.

• magniloquent - verges on bombastic more than tedious
  Adj. 1. magniloquent - lofty in style; "he engages in so much tall talk, one never really realizes what he is saying"

• grandiloquent - verges on bombastic more than tedious
  Adj. 1. grandiloquent - lofty in style; "he engages in so much tall talk, one never really realizes what he is saying"

If it said TEDIOUS talk instead of tall talk I think this might be the two words to use.

Neurotic - possible