Heurisko (εὑρίσκω) means to find — through search, discovery, or unexpected encounter. It covers: finding something after searching (the lost coin), finding something unexpectedly (finding grace), and discovering truth through investigation. The English word 'heuristic' comes from this Greek root — a method of discovery. Archimedes' famous 'Eureka!' (εὕρηκα) is the perfect tense of heurisko: 'I have found it!'
The three parables of Luke 15 all culminate in heurisko: the shepherd finds the lost sheep, the woman finds the lost coin, the father finds his lost son (in a sense). The repetition underscores that God's nature is to seek and find the lost — 'for the Son of Man came to seek and to save the lost' (Luke 19:10). Matthew 7:7-8: 'Seek and you will find; for everyone who seeks finds.' Prayer is described as seeking that results in finding. Hebrews 9:12: Christ 'securing (heuramenos) eternal redemption' — finding/obtaining redemption as the result of His priestly work.
Philippians 3:9 transforms heurisko: Paul wants to be 'found in Christ' — the ultimate discovery being not what we find but where we are found. The seeker becomes the sought. The one searching for righteousness discovers that he must be found by the Righteous One. Every spiritual quest, if honest, leads to this inversion: we are not the discoverers of God; we are the discovered of God (cf. Galatians 4:9 — 'you have come to know God, or rather be known by God').