Text annotation is the procedure of identifying the semantically dominant words of a text segment and attaching them with conceptual content information in their context. In this paper, we propose novel methods for automatic annotation of text fragments with entities of Wikipedia, the largest knowledge base online, a process commonly known as Wikification aiming at resolving the semantics of synonymous and polysemous terms accurately. The cornerstone of our contribution is a novel iterative Wikification approach, converging at optimal annotations while balancing high accuracy with performance. Our first two methods can be fine-tuned through a machine-learning technique over large homogenous data sets. Our experimental evaluation resulted in remarkable improvement over state-of-the-art Wikification approaches.