Maitri in Chinese / Japanese...

マイトリ is the name Maitri in Japanese Katakana.

Note: Because this title is entirely Japanese Katakana, it should be written by a Japanese calligrapher.

四無量心 is the cattāri brahmavihārā or catvāri apramāṇāni.

The four immeasurables, or infinite Buddha-states of mind. These four dhyānas include:
1. 慈無量心 boundless kindness, maitrī, or bestowing of joy or happiness.
2. 悲無量心 boundless pity, karuṇā, to save from suffering.
3. 喜無量心 boundless joy, muditā, on seeing others rescued from suffering.
4. 捨無量心 limitless indifference, upekṣā, i.e., rising above these emotions or giving up all things.

慈 is the simplest way to express the idea of compassion.

This can also mean love for your fellow humans, humanity, or living creatures. Sometimes this is extended to mean charity.

This term is often used in a Buddhist or Christian context. The concept was also spoken of by Laozi (Lao Tzu) in the Dao De Jing (Tao Te Ching).

慈 is considered the direct translation of the Sanskrit word मैत्री (maitrī) Pali word मेत्ता (mettā). In this context, it means benevolence, loving kindness, and goodwill.

This Chinese character is understood in Japanese but is usually used in compound words (not seen alone). Also used in old Korean Hanja, so it's very universal.

See Also:  Mercy | Benevolence | Forgiveness | Kindness

Besides the title above, 慈悲 can also be defined as clemency or lenience and sometimes the act of giving charity.

In the Buddhist context, it can be defined as “benevolence,” “loving-kindness and compassion,” or “mercy and compassion.”

This Buddhist virtue is perhaps the most important to employ in your life. All sentient beings that you encounter should be given your loving kindness. And trust me, however much you can give, it comes back. Make your life and the world a better place!

This Chinese/Japanese Buddhist term is the equivalent of Metta Karuna from Pali or Maitri Karuna from Sanskrit.

慈 can mean loving-kindness by itself.
悲 adds a component of sorrow, empathy, compassion, and sympathy for others.

See Also:  Benevolence