交換【こうかん】
exchange, interchange, switching, reciprocity, barter, substitution, replacement, clearing (of checks, cheques)
引き換え【ひきかえ】
exchange, conversion
換算【かんさん】
conversion (e.g. yen to dollars), change, exchange, translation (numerical)
換気【かんき】
ventilation
変換【へんかん】
change, conversion, transformation, transformation
乗り換え【のりかえ】
transfer (trains, buses, etc.), change, connection, switch (to another ideology, party, system, method, etc.), change, conversion, switching (stock), chromosomal crossover, crossing over
乗り換える【のりかえる】
to transfer (trains), to change (bus, train), to change (to another ideology, party, company, etc.), to switch (to a different system, method, etc.), to move on to (e.g. a new love interest)
言い換える【いいかえる】
to say in other words, to put another way, to express in different words, to reword, to rephrase