The English word saint comes from the Latin sanctus, with the Greek equivalent being ἅγιος (hagios) ‘holy’. The word ἅγιος appears 229 times in the Greek New Testament. The word sanctus was originally a technical one in ancient Roman religion, but due to its globalized use in Christianity the modern word saint is now also used as a translation of comparable terms for persons “worthy of veneration for their holiness or sanctity” in other religions.
According to the Catholic Church, a saint is anyone in Heaven, whether recognized on Earth or not, who form the “great cloud of witnesses” (Hebrews 12:1). These “may include our own mothers, grandmothers or other loved ones (cf. 2 Tim 1:5)” who may have not always lived perfect lives, but “amid their faults and failings they kept moving forward and proved pleasing to the Lord”. The title Saint denotes a person who has been formally canonized—that is, officially and authoritatively declared a saint, by the Church as holder of the Keys of the Kingdom of Heaven, and is therefore believed to be in Heaven by the grace of God. There are many persons that the Church believes to be in Heaven who have not been formally canonized and who are otherwise titled saints because of the fame of their holiness.