形容詞 prehistoric:

1. belonging to or existing in times before recorded history
   同義詞：prehistorical
2. of or relating to times before written history
3. no longer fashionable

1. The study of the forms of life existing in prehistoric or geologic times, as represented by the fossils of plants, animals, and other organisms.
   古生物學(xué)對(duì)出現(xiàn)在史前或地質(zhì)時(shí)代的生命的形成的研究，體現(xiàn)在植物、動(dòng)物和其它有機(jī)體的化石上

pre.his.tor.ic

adj.（形容詞）
Of, relating to, or belonging to the era before recorded history.
史前的：歷史記載之前的、與之相關(guān)的或?qū)儆谥?/br>Of or relating to a language before it is first recorded in writing.
有書面記載之前的語言的：有書面記載之前的語言的或與之相關(guān)的

【引伸】
pre.histor.ically
adv.（副詞）