でｌｔあ

"でｌｔあ" or simply "≜"(U+225C) is an internet slang meaning "it was supposed/meant to be blah blah blah".
"でｌｔあ" is an output when you key-in "delta" on Japanese FTPs for "≜ (delta equal to)" to emphasize "by definition" while it looks like "でしたぁ" (lt. 'was/were' but the last letter ぁ implicits 'sorry to say, but actually...' like 'umm...' in American)