This is the 8334th most frequent Japanese word.
待たさ
"待たさ" is not a standalone word; it appears to be a truncated form or typo. It might relate to 待たせる ("to make someone wait").
待たさ is used in the causative form, implying making someone wait.
待たさなければならない状況がありました。
There was a situation where I had to have others wait.
待たさ is used with passive and polite forms, expressing causing someone to wait.
待たさせてしまい申し訳ありません。
I apologize for having caused you to wait.
待たさ is used in the causative-passive form, highlighting the feeling of being made to wait.