junior
younger
subteen
two
twos
second cousin once removed
nibbling
younghead
knee baby
titch
bovver bird
twinsie
twinling
half-cousin
mersister
teenager
feely
half
contemporary
coeval
pigeon pair
ephebe
rug monkey
rugrat
our kid
halfling
cotwin
male sibling
second cousin
age-mate
sylphid
pretween
lanneret
adult third culture kid
tacker
half blood
sister
preteen
juvenile
first cousin once removed
feely-omi
brother german
grandchild
nonidentical
second grader
first cousin twice removed
elder
three
fraternal
half niece
youngest
catworm
half-uncle
maternal cousin
baby of the family
paternal cousin
half-first cousin
youthman
sesquiple first cousin
uterine sibling
lastborn
irregular double first cousin
tweenie
shaver
duo
little boy
birthmate
littlie
little brother
big brother
kipper
third cousin
peanut
loon
little sister
cousinette