The term 'even if, informally' can be expressed in two different ways in a crossword puzzle. The first is 'tho', which is an abbreviation of the phrase 'THOUGH'. This phrase is used to express a contrast between two ideas or situations, and is often used to introduce a concession or qualification. The second is 'altho', which is an alternative spelling of 'ALTHOUGH'. This is also used to express a contrast between two ideas or situations, but is more formal than 'tho'.