January \Jan"u*a*ry\, n. [L. Januarius, fr. Janus an old Latin deity, the god of the sun and the year, to whom the month of January was sacred; cf. janua a door, Skr. y[=a] to go.]

The first month of the year, containing thirty-one days.

Note: Before the adoption of New Style, the commencement of the year was usually reckoned from March 25.

Source: Webster's Revised Unabridged Dictionary (1913)