Iron-deficiency anemia can cause fatigue (tiredness), shortness of breath, chest pain, and other symptoms. Severe iron-deficiency anemia can lead to heart problems, infections, problems with growth and development in children, and other complications.
Semantics is the study of meaning. It is a wide subject within the general study of language. An understanding of semantics is essential to the study of language acquisition (how language users acquire a sense of meaning, as speakers and writers, listeners and readers) and of language change (how meanings alter over time).
Definition of subject for Students. 1  1 : the person or thing discussed : topic She's the subject of rumors. 2  2 : an area of knowledge that is studied in school Geography is my favorite subject. 3  3 : a person who owes loyalty to a monarch or state.  4 : a person under the authority or control of another.