Lexical Definition

‎φάντασμα‎ phántasma (fan'-tas-mah) ghost ^G:N-N
from ‎φαντάζω‎

spirit.

• (properly concrete) a (mere) show ("phantasm"), i.e. spectre

Abbott-Smith

φάντασμα, -τος, τό (< φαντάζω), [in LXX: Jb 20:8 A (חִזָּיוֹן), Is 28:7 A, Wi 17:15 * ;]
= φάσμα, an appearance, apparition (Æsch., al.): Mt 14:26, Mk 6:49 (v. DCG, i, 111b).†

Abbott-Smith References

Liddell-Scott-Jones

φάντασμα-μα, ατος, τό,

={φάσμα}, apparition, phantom, ἐνύπνια φαντάσματα [NT+5th c.BC+]; vision, dream, [Refs 4th c.BC+]

__b plural, phenomena, τὰ ἐν ἀέρι φ. [Refs 4th c.BC+]: plural, portents, [Refs 1st c.BC+]
__II ={φαντασία}[Refs 5th c.BC+] U.; distinguished from εἰκών, [Refs 5th c.BC+]

_{LSJ Scripture Refs: Matt.14.26}