Bound morphemes never occur in isolation, that is, are not regularly uttered alone in normal discourse. Such bound forms include prefixes, suffixes, suprafixes, infixes, replacives, subtractives, and some roots.
- Nida (1949), a pag.81

In special contexts it is always possible to employ a bound form in isolation. For example, in response to the question, 'What is this suffix?' one may reply '-ly'.
- Nida (1949), a pag.81

Stems, which consist of a root or a root plus some other morpheme, are by definition always bound, e.g. '-ceive' (cf. 'receive') and 'recep-' (cf. 'reception'), 'manli-' (cf. 'manliness') and 'formaliz-' (cf. 'formalizer').
- Nida (1949), a pag.81

Such bound forms are either (1) nonclitics -additive, replacives, subtractives- or (2) clitics. Nonclitics have a more restricted distribution and occur (for the most part) as immediate constituents with items with which they are phonologically bound. Clitics have a greater freedom of distribution and only accidentally form immediate constituents with the items with which they are phonologically bound.
- Nida (1949), a pag.103

Forms may be bound in the sense that (1) they never occur alone, e.g. the plural suffix in English, (2) they are bound alternants of free forms, e.g. /wayv-/ (cf. 'wives') in contrast with 'wife' /wayf/, (3) they occur with certain junctures, e.g. 'fresh-' in 'freshman' /fréšmən/, which is bounded by an internal (unmarked) juncture, and (4) they occur with certain suprasegmental features, e.g. '-bird' in 'blackbird' /blǽk-bə̀rd/, which occurs with a secondary stress. The particular type of external juncture is also pertinent.
- Nida (1949), a pag.105