wikipedia on the origins of easter:
the modern english term easter developed from the old english word eastre, which itself developed prior to 899. the name refers to the goddess eostre, who was celebrated at the spring equinox, and has cognates in old high german ÅstarÅ«n, plural, “easter” (modern german language ostern). the old english term eastre ultimately derives from Ä“ast – meaning the direction of east. this suggests it originally referred to a goddess associated with dawn. corresponding traditions occur with the roman goddess aurora and the greek goddess eos.
eostre is sometimes derived from the proto-germanic root *aew-s, “illuminate, especially of daybreak” and closely related to (a)wes-ter- “dawn servant”, the dawn star venus and *austrÃ´n-, meaning “dawn, east” (compare ostar-rÃ®chi “eastern realm, austria“), cognate to the names of greek eos, roman aurora and indian ushas, all continuing proto-indo-european *hausos.
there is no certain parallel to eostre in north germanic languages though grimm speculates that the east wind, “a spirit of light” named austri found in the 13th century
according to bede (c. 672 – 735), writing in de temporum ratione (“on the reckoning of time”), ch. xv, de mensibus anglorum (“the english months”) the word “easter” is derived from eostre, an anglo-saxon goddess of spring, to whom eostur-monath, corresponding to our month of april (latin: aprilis), was dedicated:
15. the english months.
in olden time the english people – for it did not seem fitting to me that i should speak of other nations’ observance of the year and yet be silent about my own nation’s – calculated their months according to the course of the moon. hence after the manner of the hebrews and the greeks, [the months] take their name from the moon, for the moon is called mona and the month monath.
the first month, which the latins call january, is giuli; february is called sol-monath; march hreth-monath; april, eostur-monath; may thrimilchi…
eostur-monath has a name which is now translated paschal month, and which was once called after a goddess of theirs named eostre, in whose honour feasts were celebrated in that month. now they designate that paschal season by her name, calling the joys of the new rite by the time-honoured name of the old observance.
what is secure in bede’s passage is that the lunar month around the month of april in the julian calendar was called eostur or similar; in vita karoli magni einhard tells, that charlemagne (c. 742 or 747 – 814) gave the months names in his own language and used ‘ostar-manoth’ for april. some critics who question bede’s account of a goddess suggest that “the anglo-saxon eostur-monath meant simply ‘the month of opening’ or ‘the month of beginnings’.” it should be noted that old high german ÅstarÅ«n is plural, as it is in aelfric‘s hexameron: “and ne beoÃ° nÃ¦fre eastron Ã¦r se dÃ¦g cume Ã°Ã¦t Ã°Ã¦t leoht hÃ¦bbe Ã°a Ã°eostre oferswiÃ°eÃ°”
in 1835, jacob grimm (1785-1863) published deutsche mythologie, a collection of german myths and oral histories, including a two-and-a-half page commentary on a goddess ostara.
grimm recalls bede’s account of eostre and states that it was unlikely that the man of the church would simply have invented a pagan goddess. from the anglo-saxon month name, he then reconstructs an old high german equivalent, *ostara:
“this ostarÃ¢, like the as [anglo-saxon/old english language]. eÃ¡stre, must in the heathen religion have denoted a higher being, whose worship was so firmly rooted, that the christian teachers tolerated the name, and applied it to one of their own grandest anniversaries.”
grimm also notes various accounts of the name of the easter festival in old high german, like Ã´stertagÃ¢ or aostortagÃ¢. according to grimm, these were plural forms of ostara, since the festival would have been celebrated on two days.
grimm’s commentary does not mention any easter eggs or easter bunny customs, the only easter custom he mentions being easter bonfires (osterfeuer), a long-standing german tradition, attested since 1559.
ostara is also one of the names of the mother-archetype in the psychology of carl gustav jung.