The Austronesian Comparative Dictionary

*isa₁ one

PAN isa₁ one

Form.
Kavalan issa one
Rukai (Budai) iθa one
Rukai iθa one
Paiwan ita one
WMP
Isneg isá one
Itawis isá one
Pangasinan isá one
Tagalog isá one; another
Hiligaynon isá one
Maranao isa one; a, an
Manobo (Western Bukidnon) isa the number one, used in counting
Samal isa one (in counting)
Kadazan Dusun iso one
Minokok isəʔ one
Bare'e isa one
Bikol isá one
Malagasy isa one
CMP
Kamarian isa one
Leti ida 'one; each, every'
Manggarai ica one
Idate isa one
Tetun ida one; a
Kodi iha one
Kambera d-iha one
iha alone, separate
SHWNG
Buli isa one
Minyaifuin pi-sa one
OC
Marau₂ eta one

PAN isa-ŋa the remaining one

Form.
Paiwan ita-ŋa there is one left
WMP
Cebuano usá-ŋa the other one of two or more

PAN isa isa distributive; one-by-one, one at a time

Form.
Paiwan ma-ita ita one by one, one after the other
WMP
Tagalog isa isa one by one, one each time
Maranao isa isa alone, only
Kadazan Dusun to-isa isa one by one, one at a time
Malagasy tsi-isa isa one by one
CMP
Tetun ida ida one by one, each one

PMP ma-isa only, alone

WMP
Chamorro maysa one (of living things)
Hanunóo maysá oneness, aloneness
Tae' misa one, alone, on its own
Sasak mésaʔ self, alone
CMP
Yamdena mésa-n single, alone (of only children)
Tetun missa-k alone, one
oan missa-k only child

Also Erai méha ‘only, alone’, and the morphological parallel in Kelabit edheh ‘one’, midheh ‘once’. Tagalog mag-isá ‘be alone, do something alone’ suggests that Hanunóo maysá may reflect *maR-isa. Mills (1975:712) posits Proto-South Sulawesi *(ma-)isa ‘one’.

PAN paR-isa-an to unite, combine in one

Form.
Puyuma paR-asa-n to do once
Puyuma (Tamalakaw) paR-asa-n to do once
WMP
Tagalog pag-isah-ín to combine (many things) into one
Old Javanese pisan once, the first one, one; at the same time, all together
Javanese pisan once, the first one, first time; at the same time; altogether
Balinese pisan first; all, complete, whole