A Weakly Typed Language, also sometimes referred to as Dynamically Typed, has looser typing rules than Strongly Typed Language and may produce unpredictable or even erroneous results, or may perform implicit type conversion at runtime. Advocates of Dynamically Typed (generally Weakly Typed) languages find such concerns to be overblown and believe that static typing actually introduces an exponentially larger set of problems and inefficiencies. A different but related concept is latent typing.
Source: https://en.wikipedia.org/wiki/Strong_and_weak_typing