- 1601 omphaloskepses
- 1602 omphaloskepsis
- 1603 omrah
- 1604 omri
- 1605 oms
- 1606 omsk
- 1607 on
- 1608 onager
- 1609 onagers
- 1610 onagra
- 1611 onagraceous
- 1612 onagri
- 1613 onan
- 1614 onanism
- 1615 onanist
- 1616 onanistic
- 1617 onanists
- 1618 onassis
- 1619 onboard
- 1620 oncall
- 1621 once
- 1622 onceayear
- 1623 oncer
- 1624 onces
- 1625 onchocerciases
- 1626 onchocerciasis
- 1627 oncidium
- 1628 oncogen
- 1629 oncogene
- 1630 oncogenesis
- 1631 oncogeneticist
- 1632 oncogenic
- 1633 oncogenicities
- 1634 oncogenicity
- 1635 oncogens
- 1636 oncologic
- 1637 oncological
- 1638 oncologies
- 1639 oncologist
- 1640 oncology
- 1641 oncolyses
- 1642 oncolysis
- 1643 oncolytic
- 1644 oncome
- 1645 oncometer
- 1646 oncomice
- 1647 oncoming
- 1648 oncomouse
- 1649 oncornavirus
- 1650 oncost
- 1651 oncostman
- 1652 oncostmen
- 1653 oncosts
- 1654 oncotomies
- 1655 oncotomy
- 1656 oncovirus
- 1657 oncredit
- 1658 oncus
- 1659 ondatra
- 1660 ondine
- 1661 onding
- 1662 ondogram
- 1663 one
- 1664 onefold
- 1665 onegin
- 1666 oneill
- 1667 oneiric
- 1668 oneirically
- 1669 oneirocritic
- 1670 oneirocritical
- 1671 oneirocriticism
- 1672 oneirocritics
- 1673 oneirodynia
- 1674 oneirologies
- 1675 oneirology
- 1676 oneiromancer
- 1677 oneiromancies
- 1678 oneiromancy
- 1679 oneiroscopies
- 1680 oneiroscopist
- 1681 oneiroscopy
- 1682 oneisone
- 1683 oneliner
- 1684 onely
- 1685 oneness
- 1686 oner
- 1687 onerier
- 1688 oneriest
- 1689 onerous
- 1690 onerously
- 1691 onerousness
- 1692 oners
- 1693 onery
- 1694 ones
- 1695 oneself
- 1696 onestep
- 1697 onetime
- 1698 oneupmanship
- 1699 oneyer
- 1700 oneyre