εἰμί
Etym. The whole of the pres. ind. (except 2nd sg. εἶ) may be enclitic when εἰμί is the Copula; but the 3rd sg. is written ἔστι in certain cases of emphasis, e. g. ἔστι μοι, "I have": when used as Verb Subst., it retains the accent in all persons.
A. as Substantive Verb, "to be, to exist", οὐκ ἔσθ᾽ οὗτος ἀνήρ, οὐδ᾽ ἔσσεται Od.; τεθνηῶτος, μηδ᾽ ἔτ᾽ ἐόντος id=Od.; οὐκέτ᾽ ἔστι he "is no more", Eur.; θεοὶ αἰὲν ἐόντες Il.; ἐσσόμενοι posterity, id=Il.; ζώντων καὶ ὄντων Ἀθηναίων Dem.:—so of cities, etc., ὄλωλεν, οὐδ᾽ ἔτ᾽ ἔστι Τροία (cf. "Troja fuit)", Eur.
II. of things, "to be, exist", εἰ ἔστιν ἀληθέως [ἡ τράπεζα] Hdt.; ἕως ἂν ὁ πόλεμος ἦι so long as it "last", Thuc.
III. "to be", opp. to "appearing to be", as "esse" to "videri", τὸν ἐόντα λόγον the "true" story, Hdt.; τὰ ὄντα ἀπαγγέλλειν Thuc.; τῶι ὄντι, Lat. revera, in reality, in fact, Plat.
IV. foll. by the Relative, οὐκ ἔστιν ὅς, "no one", Il., etc.; εἰσὶν οἵ, Lat. sunt qui, Thuc., etc.; ἐστὶν ἅ "some things", id=Thuc.; also ἔστιν οἵ, for εἰσὶν οἵ, Hdt., etc.:—so withrelat. Particles, ἔστιν ἔνθα, Lat. est ubi, Xen., etc.; ἔστιν ὅπη, ἔσθ᾽ ὅπου, "somewhere", or "somehow", Plat., etc.; ἔστιν ὅπως "in some manner", Hdt., etc.; ἔστιν ὅτε, ἔσθ᾽ ὅτε, "sometimes", Soph., etc.
V. ἔστι impers., c. inf., like πάρεστι, "it is possible", Hom., attic
B. "to be", Copula connecting predicate with subject, both being in the same case, Hom., etc.
2. sometimes εἶναι with Part. represents finite Verb, ἦν τεθνηκώς, for ἐτεθνήκει, Aesch.; πεφυκός ἐστι ῀ πέφυκε, Ar.
II. the Inf. is redundant in some phrases, ἑκὼν εἶναι (v. ἑκών II); τὸ ἐπ᾽ ἐκείνοις εἶναι "quantum in illis esset", Thuc.; τὸ σύμπαν εἶναι Hdt.; τὸ νῦν εἶναι Plat., etc.