The crossword solution for the term LTR is ENV, which stands for 'ENVELOPE'. An ENVELOPE is a flat container, usually made of paper or plastic, used to enclose documents or other items for mailing or storage. Envelopes are typically sealed by folding the flap over the opening and pressing it down. They are often decorated with stamps, seals, or other markings. Envelopes are an important part of communication and are used to send letters, cards, and other documents.