insidiate
verb
-ed/-ing/-s
transitive verb
obsolete : to plot or scheme against : lie in wait for
intransitive verb
obsolete : to lie in ambush : plot, scheme
insidiation noun
plural -s
obsolete insidiator noun
plural -s
obsolete 
Word History
Etymology
Latin insidiatus, past participle of insidiari, from insidiae ambush, from insidēre to sit in