Please help me to understand how and when english-derived words are used in modern Japanese? I understand that ko-hi and garasu didn't exist in Japan, so there are no Japanese words for them. But I found that there exist gairaigo for such words as "knife" and "husband" and many others, which obviously exited as phenomenons BEFORE . So, could you please explain and give examples from your experience? Which words are preferable where? Are they all interchangeable, can they be used in scientific speech/text, in formal speech/text?