na-adjective, noun
fine; close; delicate; intricate
Describes physical texture, grain, weave, or craftsmanship that is very fine, close, or intricately detailed.
この布は織り目が緻密で、とても丈夫だ。
This cloth has a close weave and is very durable.
彼の緻密な細工にはいつも
I'm always impressed by his delicate craftsmanship.
na-adjective, noun
precise; meticulous; careful; elaborate
Used for abstract things like plans, analysis, observation, or thinking that are carried out with great attention to detail and accuracy.
警察は緻密な捜査で犯人を特定した。
The police identified the culprit through meticulous investigation.
彼は緻密な計画を立ててから行動する。
He acts only after making an elaborate plan.
細かい is a more common, everyday word for 'fine' or 'detailed', while 緻密 emphasizes precision and intricacy, often with a nuance of high quality or carefulness.
綿密 also means 'meticulous' or 'detailed', but is used almost exclusively for abstract planning or investigation, whereas 緻密 can also describe physical fineness.
From the kanji 緻 (fine, detailed) and 密 (dense, close). The word is a Sino-Japanese compound (kango) combining these two characters to express the idea of extreme fineness and precision.