口では言い表せません。

mouth; opening; hole; gap; orifice; mouth (of a bottle); spout; nozzle; mouthpiece; gate; door; entrance; exit; speaking; speech; talk (i.e. gossip); taste; palate; mouth (to feed); opening (i.e. vacancy); available position; invitation; summons; kind; sort; type; opening (i.e. beginning); counter for mouthfuls, shares (of money), and swords

indicates location of action; at; in; indicates time of action; indicates means of action; cause of effect; by; and then; so; indicates continuing action; indicates certainty, emphasis, etc.

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

to be able to be expressed in words; to be sayable