Noun. Accidentally clicking "send" in an email or text before one has completed it or finished editing it, resulting in a less satisfying or embarrassing experience for both sender and receiver. At best, results in confusing truncated messages or typos; at worst, results in social, economic or political suicide.
When trolling for a booty call late at night, Andrew forwards the same text to multiple women. He frequently suffers from premature sendulation, accidentally leaving the wrong woman's name in the text and ensuring instant rejection.
Caitlin didn't realize she'd committed premature sendulation when she sent an email thread to her manager without stripping some choice words about her boss from the thread. She was fired.