Intensive (adjective)

1. Involving a high level of effort or activity.
2. Concentrated or intense.
3. Involved in a process or activity on a large scale or with much detail.

Origin:

Early 17th century (in the sense "intense, concentrated"): from french intensif, -ive or latin intensus "stretched tight, intense", past participle of tendere "stretch".

Examples:

1. The intensive care unit provides round-the-clock care for critically ill patients.
2. The intensive course was demanding, but he was able to pass the test.
3. The intensive research resulted in a breakthrough discovery.
4. The intensive search for the missing hiker lasted several days.
5. The intensive training program was designed to prepare athletes for the Olympics.