ثَنّى: جَعَلَهُ اثْنَيْن، ضاعَفَ to double, geminate; to duplicate; to reduplicate

ثَنّى: أعَادَ، كَرّرَ to repeat, reiterate, reduplicate, redo, do again

ثَنّى الثّوْبَ ونَحْوَه: جَعَلَ لَهُ ثَنَايا to pleat, plait, goffer

ثَنّى الحَرْفَ to provide with two diatrical points

ثَنّى الكَلِمَةَ to form the dual (of a word)

ثَنّى على اقْتِراح إلخ to second (a motion, a nomination, etc.)

ثَنّى بالأمْر: أتْبَعَهُ بآخَر to follow (up) with, cause to be followed by; to supplement with, add to