Sickerness, a somewhat obscure word, can be defined as the state or feeling of being sick. However, it is interesting to note that there are several synonyms that can be used to convey a similar meaning. Firstly, one may substitute sickerness with the more common term "illness" or "sickness", both of which capture the essence of feeling unwell. Additionally, one might use the word "malaise" to describe a general feeling of discomfort or unease. Another possibility is to employ the term "ailment", which refers to a minor health problem or affliction. These synonyms all aid in expressing the concept of sickerness and can be utilized to vary one's vocabulary.