Lexical Definition

‎παρεισέρχομαι‎ pareisérchomai (par-ice-er'-khom-ahee) to come in G:V
from ‎παρά‎ and ‎εἰσέρχομαι‎

come in privily, enter.

Usage: 2 forms in 2 verses
Form Translated As     In Verse(s)
παρεισῆλθον came in by stealth Gal.2.4
παρεισῆλθεν entered Rom.5.20

Abbott-Smith

* παρ-εισ-έρχομαι,
1. to come in beside or by the way: Ro 5:20.
2. to come in secretly, steal in: Ga 2:4.†

Abbott-Smith References

Book Refs
Romans 5:20
Galatians 2:4

Liddell-Scott-Jones

παρεισέρχομαι-έρχομαι,

with aorist and perfect active, come or go in beside: in Medicine texts, of fingers or instruments, to be inserted, [Refs 2nd c.AD+]: generally, come in, ὅπως.. τύχη παρεισέρχομαιέλθῃ [παρεισέρχομαιελθόντες ὡς φίλιοι 2nd c.BC: Polybius Historicus 1.7.3, +others; νόμος παρεισέρχομαιῆλθεν ἵνα πλεονάσῃ τὸ παράπτωμα NT.Rom.5.20; π. ἄφνω πρὸς τὴν ἑστίαν 1st-2nd c.AD: Plutarchus Biographus et Philosophus “Coriolanus” 23 ">NT+4th c.BC+]; to be introduced, of a side-issue, [Refs 2nd c.AD+]: with infinitive, π. κατασκοπῆσαι [NT]

__II occur, suggest itself, of an idea, τινι [Refs]

LSJ Scripture Refs: Rom.5.20Gal.2.4