Letter shared by many words

I'm looking for a word describing the sharing of an object (for example a letter) by other objects (for example words) such as:

• The B in Gödel, Escher, Bach: An Eternal Golden Braid as shared on the 3-dimensional ambigram on the book's cover.
• The A in this game of Scrabble.
• The I shared by WIKI and IGOR in this crossword puzzle.

In crossword lingo, a shared letter is "doubly checked". There are instances where the letter might be shared with more than two clues, as the circled letters in this puzzle, and they would be "triply checked", or "quadruply checked", etc.

You would be hard-pressed to find an answer that is "one key to every lock", but the word that you could be looking for is "overlapping" or "Intersecting" words.