Most half yearly can be replaced with terms like biannual, semiannual, or twice-yearly. These terms are used to describe events, activities, or occasions that occur twice in a year or every six months. Biannual is the most commonly used term and is interchangeable with 'semi-annual'. These terms can be used for a range of events such as payment schedules, report submissions, or even vacations. It's important to note that biannual or semiannual can sound ambiguous as it is not clear whether the first six months or the second half of the year is being referred to. As such, it is essential to state the specific period in question for clarity.