He suspected that the military were secretly plotting against him.secretlyse‧cret‧ly /ˈsiːkrɪtli/ ●●○ adverb 
They started meeting secretly.2if you feel something secretly, you do not tell anyone about your feelings: She was secretly hoping that Dan would be at the party. Secretly, Beth admired Stella’s strong character.
COLLOCATIONS FROM OTHER ENTRIES He suspected that the military were secretly plotting against him.
1if you do something secretly, you do it without other people knowing: He suspected that the military were secretly plotting against him. They started meeting secretly.2if you feel something secretly, you do not tell anyone about your feelings: She was secretly hoping that Dan would be at the party. Secretly, Beth admired Stella’s strong character.