base, bottom, minimum
Any basal structure or part
Basic, elementary; relating to, or forming, the base, or point of origin.
In a phylogenetic tree, being a group, or member of a group, which diverged earlier. The earliest clade to branch in a larger clade.
Associated with the base of an organism or structure.
Of a minimal level that is necessary for maintaining the health or life of an organism.
A fractional part of an integer ending in one
An ordinal value that is represented by an expression ending in 1 such as the (n + 1)th.
'first', or other ordinal derivatives of 'one', such as hundred-and-oneth or minus-oneth
Used at the end of algebraic expressions indicating ordinal position that end in 1, such as (k+1)ᵗʰ