ἀπό (Lesb. etc. ἀπύ) from, off, away from; originally of separation and departure. Cp. Lat. ab, Eng. off, of.
1. ἀπό with the Genitive only
a. Local: καταπηδήσᾱς ἀπὸ τοῦ ἵππου
leaping down from his horse A. 1.8.28, ἐθήρευεν ἀπὸ ἵππου he used to hunt (from a horse) on horseback 1. 2. 7, ἀπὸ θαλάσσης
at a distance from the sea 1.7. Figuratively: ἀπὸ θεῶν ἀρχόμενοι
beginning with the gods A. 6.3.18.
b. Temporal: ἀφ᾽ ἑσπέρᾱς after evening began (after sundown) A. 6.3.23, ἀπὸ τοῦ αὐτοῦ σημείου on the same signal 2. 5. 32, ἀπὸ τῶν σῑ́των after meals X. R. 5.8, ἀφ᾽ οὗ since.
c. Other relations: (1) Origin, Source: in prose of more remote ancestry: τοὺς μὲν ἀπὸ θεῶν, τοὺς δ᾽ ἐξ αὐτῶν τῶν θεῶν γεγονότας some descended (remotely) from gods, others begotten (directly) of the gods themselves 12.81. (This distinction is not always observed.) Various other relations may be explained as source.
(2) Author: as agent with passives and intransitives, when an action is done indirectly, through the influence of the agent (ὑπό of the direct action of the agent himself). Not common, except in Thuc. (chiefly with πρᾱ̓ττεσθαι, λέγεσθαι, and verbs of like meaning): ἐπρᾱ́χθη ἀπ᾽ αὐτῶν οὐδὲν ἔργον
nothing was done under their rule 1.17. The startingpoint of an action is often emphasized rather than the agent: ἀπὸ πολλῶν καὶ πρὸς πολλοὺς λόγοι γιγνόμενοι
speeches made by many and to many 8.93.
(3) Cause (remote): ἀπὸ τούτου τοῦ τολμήματος ἐπῃνέθη
he was praised in consequence of this bold deed 2.25, ταῦτα οὐκ ἀπὸ τύχης ἐγίγνετο, ἀλλ᾽ ἀπὸ παρασκευῆς τῆς ἐμῆς
this happened not from chance but by reason of the preparations I made 21.10.
(4) Means, Instrument: στράτευμα συνέλεξεν ἀπὸ χρημάτων
he raised an army by means of money A. 1.1.9; rarely of persons: ἀπ᾽ αὐτῶν βλάψαι
to do injury by means of them 7.29.
(5) Manner: ἀπὸ τοῦ προφανοῦς
openly 1.66.
(6) Conformity: ἀπὸ τοῦ ἴσου
on a basis of equality 3.10, ἀπὸ ξυμμαχίᾱς αὐτόνομοι independent by virtue of (according to) an alliance 7. 57.
N.—ἀπό with gen. is sometimes preferred to the simple gen., often for emphasis: οἱ λόγοι ἀφ᾽ ῡ̔μῶν
the words that proceed from you 6.40, ὀλίγοι ἀπὸ πολλῶν a few of the many 1. 110 (cp. 1317 a). Thuc. has many free uses of ἀπό.
2. ἀπό in Composition
From, away, off (ἀπιέναι go away, ἀποτειχίζειν wall off), in return, back (ἀποδιδόναι give back what is due, ἀπαιτεῖν demand what is one's right). Separation involves completion (hence ἀπανᾱλίσκειν utterly consume, ἀποθῡ́ειν pay off a vow), or privation and negation (ἀπαγορεύειν forbid, ἀποτυγχάνειν miss). Often almost equivalent to an intensive (ἀποφάναι speak out, ἀποδεικνύναι point out, ἀποτολμᾶν dare without reserve).