Ardent in Chinese / Japanese...

正念 is one of the Noble Eightfold Paths of Buddhism. Right Mindfulness, along with Right Effort and Right Concentration, constitute the path to Concentration or Perfect Thought.

Right Mindfulness is about remaining focused on one's body, feelings, mind, and mental qualities. It's also about being ardent, aware, and mindful, and supposes that you've already put aside worldly desire and aversion.

Monk Bhikkhu Bodhi described this as “The mind is deliberately kept at the level of bare attention, a detached observation of what is happening within us and around us in the present moment.” When practicing right mindfulness, the mind is trained to remain in the present, open, quiet, and alert, contemplating the present event.

Another definition: Ongoing mindfulness of body, feelings, thinking, and objects of thought.

This term is exclusively used by devout Buddhists. It is not a common term, and is remains an unknown concept to most Japanese and Chinese people.

See Also:  Buddhism | Enlightenment | Noble Eightfold Path

烈 is a Chinese word that means ardent; intense; fierce; stern; upright; to give one's life for a noble cause.

In another context, this character can refer to one's exploits or achievements.

In the Buddhist context, this is burning, fierce, virtuous, and/or heroic.

While technically, it had the same meaning in Japanese, it's usually a female given name, Retsu in Japanese these days.

熱愛 means love passionately, ardent love, devotion, adoration.

The literal meaning is “hot love,” as the first character means heat, fervent, hot, and warm. Sometimes it can mean fever, restlessness, or zeal. The second character is, of course, love. If you adore and are devoted to someone with all your love, this is the title for you.

貞烈 is the Japanese Kanji for “Extreme Faithfulness.”

The first Kanji means “firm adherence to one's principles,” chastity (of a woman), chaste, etc.

The second Kanji means ardent, intense, fierce, stern, upright, to give one's life for a noble cause, exploits, achievements, virtuous, and in some contexts, heroic.

Now you get the idea why this refers to someone who is extremely faithful (to a cause, themselves, their religious beliefs, or their philosophy.