Structure
What are the elements that make up this word's structure?
After we study the inflectional suffixes, one of the first suffixes I usually teach students is
meticul + ous
I'm guessing that first piece can be analyzed into further elements. It might be <-ule>, which has several functions when found as a suffix. It could also be molecule.
However, although our intuition gets better and better the more we practice scientific word study, we still must use evidence. For this, I often turn to the Online Etymological Dictionary. The entry for meticulous states that this word came to us in the 1500s and initially meant "timid." This sense has become obsolete.
The entry goes on to show us the word originally is from Latin metus, "fear; dread." Words take strange journeys from an orthographic denotation of "fear; dread" to "carefully and in great detail."
mete/ + icule/ + ous
The slash marks indicate
I'm going with the latter. The entry in wiktionary suggested an analogous relationship with periculosus, which they analyze further to culosus.
mete/ + i + cule/ + ous