Is it ensure, insure, or assure?
late 14c., originally especially in reference to Feast of the Purification of the Virgin Mary, from Old French purificacion, from Latin purificationem (nominative purificatio) "a purifying," noun of action from past participle stem of purificare (see purify). General sense from 1590s.
early 14c., "free from spiritual pollution," from Old French purefier "purify, cleanse, refine" (12c.), from Latin purificare "to make pure," from purus "pure" (see pure) + root of facere "to make" (see factitious). Meaning "free from extraneous matter" is recorded from mid-15c. Related: Purified; purifying.
the process by which a person unclean, according to the Levitical law, and thereby cut off from the sanctuary and the festivals, was restored to the enjoyment of all these privileges. The great annual purification of the people was on the Day of Atonement (q.v.). But in the details of daily life there were special causes of cermonial uncleanness which were severally provided for by ceremonial laws enacted for each separate case. For example, the case of the leper (Lev. 13, 14), and of the house defiled by leprosy (14:49-53; see also Matt. 8:2-4). Uncleanness from touching a dead body (Num. 19:11; Hos. 9:4; Hag. 2:13; Matt. 23:27; Luke 11:44). The case of the high priest and of the Nazarite (Lev. 21:1-4, 10, 11; Num. 6:6, 7; Ezek. 44:25). Purification was effected by bathing and washing the clothes (Lev. 14:8, 9); by washing the hands (Deut. 21:6; Matt. 27:24); washing the hands and feet (Ex. 30:18-21; Heb. 6:2, "baptisms", R.V. marg., "washings;" 9:10); sprinkling with blood and water (Ex. 24:5-8; Heb. 9:19), etc. Allusions to this rite are found in Ps. 26:6; 51:7; Ezek. 36:25; Heb. 10:22.
in chemistry, separation of a substance into its components and the removal of impurities. There are a large number of important applications in fields such as medicine and manufacturing.