- Thorough; to a great degree; with intensity.
Secondly, I continue to base my concepts on intensive study of a limited suite of collections, rather than superficial study of every packet that comes to hand.
- Demanding; requiring a great amount of work etc.
This job is difficult because it is so labour-intensive.
- Highly concentrated.
I took a three-day intensive course in finance.
(obsolete) Stretched; allowing intension, or increase of degree; that can be intensified.
Characterized by persistence; intent; assiduous.
The polysemy displayed by the definitions shows some senses that fit very well, others that don't. I'm inclined to think that it would be better with a qualifying noun attribute for clarity
Washing the dishes is not a labor-intensive task
Writing an essay is a time-intensive task.
Yet, the metonym of both senses is not in my humble opinion intensive. Writing a stackexchange answer for example should rarely be an intensive task. We up-vote extensive answers, but discourage trivial drivel.
Between extent/intent, intention/extension, the sense that does fit the wanted meaning is not readily recognizable from the stem(s). Yet, a literal translation to Ger an-strengend confirms my idea, where streng obviously compares to strength, tension. Eventually the prefix does occlude the idea. Compare instead tedious, strainious (in which, I do note so frequently, s- may be tried as a prefix ca. ex- "out" itself, compare "utmost" for the intensifying sense of "out").