is 猶 actually a bad luck word or am i crazy

so I saw 猶 on a screen and i think someone told me it's only for like... death row stays or scary 疾患 (disease?) stuff?? is that real or a myth? maybe it just means 'still' but my friend said never use it. also wait is 一昨 the day before yesterday or is that something else? i always mix them up and now im worried 猶 is going to make me sound super irresponsible or something lol help