A type of (verbal) truth;
on the basis of common characteristic, to use figure of speech like simile or metaphor for
describing anything; e.g. (her) eyes are like lotus. Here comparison of eyes with lotus is made on the basis of the fact that both are opening.
daśamamaupamyasatyamiti upamaivaupamyam tena satyamanpamyasatyam yathā samudravattadāgam devo'yam simhastvamiti, sarvatraikārah prathamaikavacanārthe drastavya iheti.
(Sthā 10.89 Vṛ Pa 464)