必不可缺

see 必不可少[bi4 bu4 ke3 shao3]

no; not so / (bound form) not; un-

can / may / able to / to approve / to permit / to suit / (particle used for emphasis) certainly / very

used in 可汗[ke4 han2]

cannot / should not / must not

cannot; should not; must not

deficiency / lack / scarce / vacant post / to run short of

certainly / must / will / necessarily