The generated text by Natural Language Generation (NLG) and template systems is meaningful and looks legitimate. Therefore, the Mature Linguistic Steganography Methodology (Matlist) employs NLG and template techniques along with Random Series values (RS), e.g. binary, decimal, hexadecimal, octal, alphabetic, alphanumeric, etc., of Domain-Specific Subject (DSS) to generate noiseless text-cover. This type of DSS, e.g. financial, medical, mathematical, scientific, economical, etc., has plenty of room to conceal data and allows communicating parties to establish a covert channel such as a relationship based on the profession of the communication parties to transmit a text-cover. Matlist embeds data in a form of RS values, function of RS, related semantics of RS, a combination of these, etc. Unlike synonym-based approach, Matlist does not preserve the meaning of text-cover every time it is used. Instead, Matlist Cover retains different legitimate meaning for each message while it remains semantically coherent and rhetorically sound. The presented implementation, validation, and experimental results demonstrate that Matlist is capable of accomplishing the steganographical goal with higher bitrate than all other linguistic steganography approaches.