Mum's the word

All words relate to the concept of 'Mum's the word'

Think about what these words have in common

Look for the Spangram - it often reveals the theme

Theme words range from 5 to 9 letters long

Several words share similar endings

Each theme word starts with a different letter

One word: H______ (6 letters, starts with 'H')

Another word: I______ (9 letters)

Also look for: M______ (5 letters)