The Collaborative International Dictionary of English v.0.48:

Habitual \Ha*bit"ual\ (h[.a]*b[i^]t"[-u]*al; 135), a. [Cf. F.
   habituel, LL. habitualis. See Habit, n.]
   1. Formed or acquired by habit or use.
      [1913 Webster]

            An habitual knowledge of certain rules and maxims.
                                                  --South.
      [1913 Webster]

   2. According to habit; established by habit; customary;
      constant; as, the habitual practice of sin.
      [1913 Webster]

            It is the distinguishing mark of habitual piety to
            be grateful for the most common and ordinary
            blessings.                            --Buckminster.

   Syn: Customary; accustomed; usual; common; wonted; ordinary;
        regular; familiar. -- Ha*bit"u*al*ly, adv. --
        Ha*bit"u*al*ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

habitual
    adj 1: commonly used or practiced; usual; "his accustomed
           thoroughness"; "took his customary morning walk"; "his
           habitual comment"; "with her wonted candor" [syn:
           accustomed, customary, habitual, wonted(a)]

Moby Thesaurus II by Grady Ward, 1.0:

82 Moby Thesaurus words for "habitual":
   accepted, accustomed, addicted, arranged, automatic, average,
   beaten, businesslike, chronic, common, commonplace, confirmed,
   constant, continual, conventional, current, customary, established,
   everyday, familiar, fixed, formal, frequent, frequentative,
   habituated, hackneyed, hardened, harmonious, household, in hand,
   ingrained, instinctive, inveterate, involuntary, many, many times,
   methodical, natural, normal, normative, not rare,
   of common occurrence, oft-repeated, oftentime, ordered, orderly,
   ordinary, perpetual, persistent, popular, predominating,
   prescriptive, prevailing, prevalent, recurrent, recurring, regular,
   regulation, repetitive, ritual, rooted, routine, set, settled,
   standard, steady, stereotyped, stock, symmetrical, systematic,
   thick-coming, traditional, trite, uniform, universal, usual,
   vernacular, well-ordered, well-regulated, well-trodden, well-worn,
   wonted