1. A system for generating requirements specification to develop functionalities of a software, the system comprising: a processor; and a memory coupled to the processor, wherein the memory comprises, a mapping module configured to map knowledge elements of at least one ontology instance for a domain, selected from among a plurality of ontology instances in a knowledge base, with another ontology instance, selected from among the plurality of ontology instances based on an input received from a user and wherein the ontology instance defines a common vocabulary, in a machine-readable and processable format, for users who share information within the domain associated with the software being developed, for which the requirements specification is being generated, wherein the mapping module includes a plurality of bridge classes to specify semantic mappings of conclusions drawn from at least one said plurality of ontology instances; and an agile recommendation module configured to, generate a knowledge corpus from the knowledge base based on the mapped knowledge elements and one or more environmental parameters selected by the user, wherein: the one or more environmental parameters are selected to define requirements for developing functionalities of the software; the one or more environmental parameters include a geographic region; and the knowledge corpus includes features and associated knowledge elements based on the selected one or more environmental parameters; receive at least one modification in the knowledge corpus based on a selection of one or more of the features and the associated knowledge elements in the knowledge corpus by the user, wherein the selection includes one of a modification and enhancement of the features and the associated knowledge elements; generate recommendations specific to the domain from the knowledge base based on the received at least one modification, said generation facilitated by using a plurality of lexical decomposition techniques to resolve a plurality of requirement descriptions; and generate the requirements specification for the domain by incorporating the user's response to the recommendations, wherein the requirements specification indicates prioritization of a plurality of iterations, the plurality of iterations being indicative of logical and coherent units of functionalities of the software to be developed; and an extraction module configured to, apply at least one inference rule on the plurality of ontology instances in the knowledge base to identify an ontology instance from among the plurality of ontology instances based on the selected one or more environmental parameters; and extract semantic inferences from the identified ontology instance by matching the selected one or more environmental parameters and the mapped knowledge elements to provide the knowledge corpus.