first generation
first glance
first goal
first grade
first graft
first group
first growing season
first half
first harmonic
first harvest
first hospitalization
first hour

first hypothesis
first identification
first impressions
first increases
first indication
first indicators
first infant
first infusion
first injection
first insights
first instance
first intercourse
first intervention

first interview
first introduction
first intron
first investigation
first isolated
first isolation
first issue
first iteration
first job
first kind
first lactation
first language
first layer

first leaf
first level
first line
first line investigation
first line therapy
first line treatment
first link
first male
first mandibular molar
first manifestation
first marriage
first mating
first maturity

first measurements
first meeting
first member
first metabolite
first method
first millennium BC
first minute
first mode