Synonyms:

duhkhesu–in the threefold miseries; anudvigna-manah–without being agitated in mind; sukhesu–in happiness; vigata-sprhah–without being too interested; vita–free from; raga–attachment; bhaya–fear; krodhah–anger; sthita-dhih–one who is steady; munih–a sage; ucyate–is called.

Translation:

One who is not disturbed in spite of the threefold miseries, who is not elated when there is happiness, and who is free from attachment, fear and anger, is called a sage of steady mind.