foilsigh, v.t. 1. Reveal, disclose, make manifest. An fhírinne a fhoilsiú, to reveal the truth. Rún a fhoilsiú, to disclose a secret. Rud a foilsíodh dó in aisling, something he was shown in a vision. Foilseoidh Dia an éagóir orthu, God will expose their iniquity. D’fhoilsigh sé é féin sa doras, he appeared at the door. 2. Publish. Leabhar a fhoilsiú, to publish a book. Litir fhoilsithe, open letter.