jemand

German

From Middle High German jeman, ieman, iemant, from Old High German ioman, eoman, equivalent to je +‎ man.

jemand m

Jemand is synonymous with einer (“someone”), which is the nominalised masculine form of the numeral ein (“one”). In written German, jemand is more common than einer, whereas colloquial German often prefers the latter. (Note that einer can also be used in other senses, in which jemand is not applicable.) Another synonym used exclusively in the vernacular is wer (originally meaning “who”).
Jemand may or may not take the case endings -em (dative) and -en (accusative). Thus: “Ich suche jemand” and “Ich suche jemanden” are both correct translations of “I'm looking for somebody.” The latter is somewhat more common (at least in writing). Using jemanden in the dative is incorrect, but it's a common error and occurs with surprising frequency in print.
With a following adjective, jemand is always uninflected. The adjective itself is capitalized and declined in the strong pattern. It generally uses neuter forms: jemand Neues – "somebody new". In the accusative case it may also take a masculine form: “Ich suche jemand Neuen” alongside “Ich suche jemand Neues.” ("I'm looking for somebody new.") The dative form has -em either way. The genitive case cannot be used with an adjective, but needs to be paraphrased.