consideryoudaoicibaDictYouDict[consider 词源字典]
consider: [14] Etymologically, consider means ‘observe the stars’. Amongst the most popular of ancient Roman methods of divination was astrology, and so the Latin verb consīderāre was coined (from the intensive prefix com- and sīdus ‘star’, source of English sidereal) to describe the activity of carefully noting the stars’ courses for the purpose of drawing auguries.

From ‘observing stars’ it soon broadened out in meaning to simply ‘observe’, and hence figuratively ‘think over something’, but the sense ‘have an opinion’ seems to be an English development of the 16th century. English acquired the word via Old French considerer, but borrowed considerable directly from Latin consīderābilis; the modern sense ‘large in amount’ arose in the mid-17th century, on the basis of an earlier ‘worthy of consideration because of great quantity’.
=> desire, sidereal[consider etymology, consider origin, 英语词源]
consider (v.)youdaoicibaDictYouDict
late 14c., from Old French considerer (13c.) "reflect on, consider, study," from Latin considerare "to look at closely, observe," perhaps literally "to observe the stars," from com- "with" (see com-) + sidus (genitive sideris) "constellation" (see sidereal).

Perhaps a metaphor from navigation, but more likely reflecting Roman obsession with divination by astrology. Tucker doubts the connection with sidus, however, because it is "quite inapplicable to desiderare," and suggests derivation instead from the PIE root of English side meaning "stretch, extend," and a sense for the full word of "survey on all sides" or "dwell long upon." Related: Considered; considering.