The Collaborative International Dictionary of English v.0.48:

natural family \nat"u*ral fam"i*ly\, n. (Biol.)
   a group of living organisms classed as a family in a
   toxonomic classification.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Family \Fam"i*ly\, n.; pl. Families. [L. familia, fr. famulus
   servant; akin to Oscan famel servant, cf. faamat he dwells,
   Skr. dh[=a]man house, fr. dh[=a]to set, make, do: cf. F.
   famille. Cf. Do, v. t., Doom, Fact, Feat.]
   1. The collective body of persons who live in one house, and
      under one head or manager; a household, including parents,
      children, and servants, and, as the case may be, lodgers
      or boarders.
      [1913 Webster]

   2. The group comprising a husband and wife and their
      dependent children, constituting a fundamental unit in the
      organization of society.
      [1913 Webster]

            The welfare of the family underlies the welfare of
            society.                              --H. Spencer.
      [1913 Webster]

   3. Those who descend from one common progenitor; a tribe,
      clan, or race; kindred; house; as, the human family; the
      family of Abraham; the father of a family.
      [1913 Webster]

            Go ! and pretend your family is young. --Pope.
      [1913 Webster]

   4. Course of descent; genealogy; line of ancestors; lineage.
      [1913 Webster]

   5. Honorable descent; noble or respectable stock; as, a man
      of family.
      [1913 Webster]

   6. A group of kindred or closely related individuals; as, a
      family of languages; a family of States; the chlorine
      family.
      [1913 Webster]

   7. (Biol.) A group of organisms, either animal or vegetable,
      related by certain points of resemblance in structure or
      development, more comprehensive than a genus, because it
      is usually based on fewer or less pronounced points of
      likeness. In Zoology a family is less comprehesive than an
      order; in botany it is often considered the same thing as
      an order.
      [1913 Webster]

   Family circle. See under Circle.

   Family man.
      (a) A man who has a family; esp., one who has a wife and
          children living with him and dependent upon him.
      (b) A man of domestic habits. "The Jews are generally,
          when married, most exemplary family men." --Mayhew.

   Family of curves or Family of surfaces (Geom.), a group
      of curves or surfaces derived from a single equation.

   In a family way, like one belonging to the family. "Why
      don't we ask him and his ladies to come over in a family
      way, and dine with some other plain country gentlefolks?"
      --Thackeray.

   In the family way, pregnant. [Colloq. euphemism]
      [1913 Webster]

WordNet (r) 3.0 (2006):

family
    n 1: a social unit living together; "he moved his family to
         Virginia"; "It was a good Christian household"; "I waited
         until the whole house was asleep"; "the teacher asked how
         many people made up his home" [syn: family, household,
         house, home, menage]
    2: primary social group; parents and children; "he wanted to
       have a good job before starting a family" [syn: family,
       family unit]
    3: a collection of things sharing a common attribute; "there are
       two classes of detergents" [syn: class, category,
       family]
    4: people descended from a common ancestor; "his family has
       lived in Massachusetts since the Mayflower" [syn: family,
       family line, folk, kinfolk, kinsfolk, sept,
       phratry]
    5: a person having kinship with another or others; "he's kin";
       "he's family" [syn: kin, kinsperson, family]
    6: (biology) a taxonomic group containing one or more genera;
       "sharks belong to the fish family"
    7: a loose affiliation of gangsters in charge of organized
       criminal activities [syn: syndicate, crime syndicate,
       mob, family]
    8: an association of people who share common beliefs or
       activities; "the message was addressed not just to employees
       but to every member of the company family"; "the church
       welcomed new members into its fellowship" [syn: family,
       fellowship]

Moby Thesaurus II by Grady Ward, 1.0:

199 Moby Thesaurus words for "family":
   affiliation, agnate, ancestors, ancestry, animal kingdom,
   antonomasia, apparentation, ashram, binomial nomenclature,
   biosystematics, biosystematy, biotype, birth, blood,
   blood relation, blood relative, bloodline, body, branch, breed,
   brood, caste, children, clan, clannish, clansman, class,
   classification, cognate, collateral, collateral relative, colony,
   common ancestry, commonwealth, commune, community, connections,
   consanguinean, consanguinity, deme, derivation, descendants,
   descent, diphyletic, direct, direct line, distaff side,
   distant relation, division, dynasty, economic class, enate,
   endogamous group, ethnic, extended family, extraction, family tree,
   female line, filiation, flesh, flesh and blood, folk, folks,
   forebears, forefathers, fruit, genealogical, genealogy, genetic,
   genotype, genre, gens, gentile, gentilic, genus, german, get,
   glossology, grandchildren, great-grandchildren, group, hearth,
   heirs, home, homefolks, hostages to fortune, house, household,
   inheritors, issue, kids, kin, kind, kindred, kinfolk, kingdom,
   kinnery, kinsfolk, kinship group, kinsman, kinsmen, kinswoman,
   kith and kin, line, line of descent, lineage, lineal, little ones,
   male line, matriclan, menage, moiety, nation, national,
   near relation, new generation, next of kin, nomenclature,
   nuclear family, offspring, onomastics, onomatology, order,
   orismology, parentage, patriclan, pedigree, people, phratria,
   phratry, phyle, phyletic, phylogenetic, phylum, place-names,
   place-naming, plant kingdom, polyonymy, posterity, progenitors,
   progeny, race, racial, relations, relatives, rising generation,
   section, seed, sept, series, set, settlement, sib, sibling, side,
   social class, society, sons, spear kin, spear side, species,
   spindle kin, spindle side, stem, stirp, stirps, stock, strain,
   subcaste, subclass, subdivision, subfamily, subgenus, subkingdom,
   suborder, subspecies, subtribe, succession, superclass,
   superfamily, superorder, superspecies, sword side, systematics,
   taxonomy, terminology, toponymy, totem, totemic, treasures, tribal,
   tribe, tribesman, trinomialism, type, uterine kin, variety,
   younglings, youngsters



Bouvier's Law Dictionary, Revised 6th Ed (1856):

FAMILY, domestic relations. In a limited sense it signifies the father,
mother, and children. In a more extensive sense it comprehends all the
individuals who live under the authority of another, and includes the
servants of the family. It is also employed to signify all the relations who
descend from a common ancestor, or who spring from a common root. Louis.
Code, art. 3522, No. 16; 9 Ves. 323.
     2. In the construction of wills, the word family, when applied to
personal property is synonymous with kindred, or relations. It may,
nevertheless, be confined to particular relations by the context of the
will, or may be enlarged by it, so that the expression may in some cases
mean children, or next of kin, and in others, may even include relations by
marriage. 1 Rop. on Leg. 115 1 Hov. Supp. 365, notes, 6 and 7; Brown v.
Higgs; 4 Ves. 708; 2 Ves. jr. 110; 3 East, Rep. 172 5 Ves. 156 1,7 Ves. 255
S. 126. Vide article Legatee. See Dig. lib. 50, t. 16, 1. 195, s. 2.