clandestinely
From LSJ
ἀγαπήσεις τὸν πλησίον σου ὡς σεαυτόν → love your neighbor as yourself, thou shalt love thy neighbour as thyself, love thy neighbour as thyself
P. and V. λάθρα, λαθραίως (rare P.), P. κρύφα, Ar. and P. κρύβδην, V. κρυφῆ; (also Xen.), κρυφαίως, κρύβδα.