plural of fil de fer

soldering iron (tool)

(fencing) to cross swords (to place or hold two swords so they cross each other) / (figuratively) to cross swords, to lock horns, to duel [+ avec (someone)]

(transitive) to brand (to burn the flesh with a red-hot iron, as a marker) / (transitive, figuratively) to leave a deep impression on, to mark for life

(simile, informal) to firmly believe in, to be firmly convinced of [+ à (something)]

plural of fil de fer barbelé

barbed wire

(simile) to be a very poor swimmer

(figuratively) to strike while the iron is hot, to make hay while the sun shines

Alternative form of battre le fer pendant qu'il est chaud