four-month-old
UK[ˌfɔː ˈmʌnθ ˌəʊld]US[ˌfɔr ˈmʌnθ ˌoʊld]
adj
Being four months of age
n
A person or animal that is four months old
Morpheme Breakdown
four
month
old
four
month
old
Etymology
The compound "four-month-old" is a modern English construction following a transparent Germanic pattern for specifying age. Its first element, "four," descends from the Proto-Indo-European root kʷetwóres, which evolved into the Proto-Germanic fedwōr and Old English 'fēower'. The second element, "month," originates from the Proto-Germanic mēnōth-, derived from mēnô (moon), reflecting the ancient lunar calendar. The final element, "old," stems from the Proto-Germanic aldaz, meaning "grown up" or "aged." The compound's logic is purely descriptive, sequentially combining a number, a standard unit of time, and a state of being to denote a precise duration of existence, a formulaic method common in English for ages and durations.
Analysis
Structure: four + month + old
- four: From Old English 'fēower', of Proto-Germanic origin, related to Latin 'quattuor'. Functions as a numerical root.
- month: From Old English 'mōnath', related to 'mōna' (moon), of Proto-Germanic origin. Functions as a temporal unit.
- old: From Old English 'eald', of Proto-Germanic origin. Functions as an adjective indicating age.
Examples
The four-month-old puppy is already learning to follow commands.
They have a four-month-old daughter who just started smiling.
The study observed the sleep patterns of four-month-olds.